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Full text of "The newer knowledge of nutrition : the use of food for the preservation of vitality and health"

.NEWER KNOWLEDGE 
■;::■ NUTRITION 

uL USE OF FOODS FOR, THE 
tVATlON OF VITAUTY ANO HEALFH 



MS COLLUM' 



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3 1924 104 2^ 937^ 



Cornell University 
Library 



The original of this book is in 
the Cornell University Library. 

There are no known copyright restrictions in 
the United States on the use of the text. 



http://archive.org/details/cu31924104225937 



THE NEWER KNOWLEDGE OF NUTRITION 



THE MACMILLAN COMPANY 

NEW VOEE ■ BOSTON ■ CHICAGO • DMJJiS 
ATLANTA ■ SAN fRAHCISCO 

fcACMILLAN & CO., Limited 

LONDON - BOUBAY 'CALCUTTA 
UELBOmtNE 

THE MACMILLAN CO. OF CANADA, Ltd. 

TOSOHTO 



THE NEWER KNOWLEDGE 
OF NUTRITION 



THE USE OF FOOD FOR THE PRESERVATION 
OF VITALITY AND HEALTH 



BY 
E. V. McCOLLUM 

SCHOOL OP HYGIENE AND PUBLIC HEALTH, THE 
JOHNS HOPKINS UNXVEBSITT 



ILLUSTRATED 



THE MACMILLAN COMPANY 
1919 

AU rights reserved 

i;( v: V(>l;K i i A'l i 
( ir l;AfcV 






.NS- 



Coiplxftak!^, 1918 
By the MACMILLAN COMPANY ' 
Set up and eleotrotyped. Published October, 1918. 







PREFACE 

The need for knowledge of nutrition was never 
greater than at the present time when so large a 
part of the energies of the people of Europe and 
America are absorbed in the activities of war. The 
demoralization of agriculture over wide areas, to- 
gether with the shortage of tonnage for the trans- 
portation of food, have reduced the food supply of 
a number of nations to the danger point, and have 
cut off in great measure the opportunity for securing 
the variety which exists in normal times. 

The investigations of the last few years have, 
fortunately, led to great advancement in our knowl- 
edge of what constitutes an adequate diet. Such 
knowledge can, if rightly appUed, greatly assist in 
enabhng us to make use of oiu- food supply in a 
manner which will avoid mistakes sufficiently serious 
to become reflected in a lowering of our standard 
of pubhc health. It seems certain that pellagra is 
the sequel to the adherence to a faulty diet for such 
a period as to materially reduce the powers of re- 
sistance of the body to infection, and reasons are 
presented in support of the view that there is a 



vi PREFACE 

much closer relationship between the character of 
the diet and the incidence of tuberculosis than lias 
hitherto been beheved. This view is offered in the 
present disciission as an invitation to criticism, in 
the hope that new data either in support or refuta- 
tion of its vaUdity will be presented. If it shall be 
. definitely proven that faulty diet is the chief factor 
in the etiology of this disease, and that pellagra, 
is, as the Thompson-McFadden Commission, JobUng 
and Peterson and others beUeve, cavsed by infection, 
it will estabUsh that, as the author suggests, large 
groups of people are at the present time making 
serious errors in the selection of foods. Regardless 
of the outcome of future studies relating to the im- 
portance of diet to the etiology of these diseases, a 
non-technical presentation of the kinds of combina- 
tions of our natural foods vdiich induce good or 
faulty nutrition in animals, should be of service in 
showing the inadequacy of the practice, which is 
still in vogue, of regarding calories as the factor of 
prime importance in the planning of the diet 

From the data discussed in the following pages it 
will be evident that the idea that freedom of choice, 
and variety of food sources for the diet will prevent 
any faults in the diet from becoming serious, is no 
longer tenable, especially if one is wilUng to admit 



PREFACE , vn 

the existence of many degrees of gradation of mal- 
nutrition, not recognizable except in their effects on 
the individual over a long period of time. The 
author recently enjoyed with a friend, a dinner 
which consisted of steak, bread made without milk, 
butter, potatoes, peas, gravy, a flavored gelatin 
dessert and coffee. The meal was appetizing and 
satisfjdng, but such a diet of seeds, tubers and meat 
would not promote health in an experimental animal 
over a very long period. 

The Uterature which has a bearing on the apphca- 
tion of modem research to the practical problems 
of himian nutrition has become somewhat extensive 
and is scattered in technical journals, and is not 
readily accessible, dr easy to read in proper sequence. 
During the present year the author had the pleasure 
of presenting an interpretation of this literature in 
the Thomas Clarence Cutter Lectures at the Harvard 
Medical School. Believing that the publication of 
these lectures would serve' to answer many of the 
questidns which have been asked in numerous letters 
from the pubUc, they have been edited and presented 
in their present form. 

It is a pleasure to acknowledge the author's in- 
debtedness to those who have assisted in carrying 
out the experimental work which made possible the 



VlU PREFACE . 

discussion of nutrition offered in this book. Nearly 
three thousand feeding experiments varying in length 
from six weeks to four years have been observed. 
Special appreciation should be accorded to Mi§s 
Marguerite Davis who assisted with the early work, 
in'the first two years of which no interpretation of 
the cause of success or failure of our experimental 
animals was possible, and to Miss Nina Simmonds 
and Miss Helen T. Parsons for their keen interest 
and never-failing loyalty to the work. 

E. V. McCOLLUM. 

The Johns Hopkins Univebsity 
School of Hygiene and Public Health, 
Baltimore, Md. 



CONTENTS 

CHAPTER PAGE 

I. The Biological Method for the Analysis op a 
Food-stuff 1 

II. Experimental Scurvy and the Dietary Properties 

OF Vegetables .- 34 

III. The Vegetarlau Diet 53 

IV. The Foods of Animal Origin 69 

V. The Diseases Referable to Faulty Diet, or the 

So-called "Deficiency Diseases" 83 

VI. The Nursing Mother as a Factor op Safety in the 

Nutrition of the Suckling 116 

VII. Practical Considerations which Should Guide in 

THE Planning of the Diet 130 

Introduction to the Legends to the Charts . . . 154 

Bibliography 191 

Index 197 



THE NEWER KNOWLEDGE OF NUTRmON 



THE NEWER 
KNOWLEDGE OF NUTRITION 

CHAPTER I 

THE BIOLOGICAL METHOD FOB THE ANALYSIS OF A 
FOOD-STUFF 

Our knowledge of nutrition has progressed hand 
in hand with the development of the science of 
Chemistry. Chemical science gave us the clue to an 
understanding of the nature of the food-stuffs and 
the changes which take place in digestion, as well 
as an appreciation of some of the secrets of the 
metabolic processes which take pl3,ce within the 
tissues of the body. Chemistry will continue, as 
time goes on, to aid in extending our knowledge of 
the finer processes of physiology. Nevertheless, 
it has been possible for a time to advance very rapidly 
in the study of nutrition, from the technical as well 
as from the practical standpoint, by a systematic 
feeding of simplified diets to animals. The results 
were interpreted on the observations as to the abUity, 
or failure, of the animals to develop normally, as 
the diets were modified. Progress has resulted in 
the past, and will continue in the future to come 
from the judicious division of labor between the 

1 



2 THE NEWER KNOWLEDGE OF NUTRITION 

study of food problems by chemical methods, and 
by animal experimentation. In this brief exposition 
of the present situation respecting our knowledge of 
foods and nutrition, it is desirable that the reader 
should appreciate the viewpoint of the investigator, 
and should understand the line of reasoning by which 
the successive steps in the progress of the last few 
years have been attained. A brief historical account 
of the steps by which research in this field have been 
developed will serve this purpose, and at the same 
time, wiU illustrate the mental processes of a student 
engaged in the task of bringing order into a field of 
scientific inquiry where before there was no clear 
understanding. 

A plant structure, or an animal body is an exceed- 
ingly complex mixture of chemical substances, many 
of which are themselves individually as comphcated 
in their structure as the most complex machine. 
The first step in the direction of reaching an under- 
standing of the chemistry of the living mass, must 
involve the separation and study of the structural 
units of which the tissues are composed. This was, 
indeed, the field of activity of many organic and 
physiological chemists during the nineteenth century. 
The fats and the simpler substances into which they 
can be converted as in soap making; the starches and 
the sidaplef sugars, and the manner in which they 
are related chemically; the proteins, bodies having 
the properties of egg white, the casein of milk, hair, 
etc., yet very closely related in their chemical nature, 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 3 

since they can all be resolved into the same digestion 
products in the animal body, or in the chemical 
laboratory, have all been carefully studied and with 
marked success. These and a long Ust of a thousand 
or more relatively simple chemical substances have 
been discovered, and isolated in a state of purity from 
plant and animal tissues. They have been studied 
to determine their special properties, composition 
and the tests by means of which they may be recog- 
nized and identified. 

Through a century of patient labor by many able 
men, an understanding of the number and character 
of simple structural units iato which the tissues of 
animal or plant can be separated, became reaUzed. 
Furthermore, certain of these simple bodies could be 
recognized as intermediate products on their way 
toward being built up into the most highly organized 
units of the Uving tissues; others were shown to be 
degradation products resulting from the physiological 
activity of the Uving tissues of the plant or animal. 
Through these studies it became estabUshed that, the 
body of an animal or the tissues of a plant consists 
essentially of: proteins, which are peculiar in that 
they contain about sixteen per cent of the element 
nitrogen, and are complex in structure; starch-Uke 
substances and sugars, into which the starches can 
be easily converted, and fats and a number of closely 
related, and, in many respects, similar substances 
known collectively as lipoids. With these there are 
always associated in the living tissues more or less 



4 THE NEWER KNOWLEDGE OF NUTRITION 

water and a number of mineral salts. Num'?rous 
special varieties of each of these types of substances 
became known, and their less obvious characteristics 
were described. Certain substances were found to 
be special products, found only at certain times and 
in certain special locahties, and these became re- 
garded in their true light, as of subordinate interest. 
Examples of such are the alkaloids, quinine, strich- 
nine, etc., the cellulose which serves as skeletal tissue 
for the plant but is not necessary for the animal, and 
in the same category belong the waste products of 
the life processes of the animal body, most of which 
are not found in plant substances. Living tissues, 
although always associated with numerous sub- 
stances, the exact importance of which could not 
be determined, were found to consist essentially of 
the proteins, fats, sugars, mineral salts and water. 
These came to be regarded even as early as 1840, as 
the essential and never failing constituents of plant 
tissues and were regarded as the essential constituents 
of an adequate diet for an animal. 

The processes of the digestion of food have excited 
the wonderment and have occupied the patient 
attention of some of the most earnest students of 
physiology and biochemistry. The chemistry of the 
fats, and the starches and sugars being simpler, or 
rather less complex than that of the proteins, came 
to be earUer understood in their essential features. 
It was not until toward the close of the nineteenth 
century that the nature and extent of protein diges- 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 5 

tion became clearly appreciated. Soon after 1900 
the researches of Fischer revealed the great variation 
in the composition of proteins from different sources.^ 
This discovery introduced into nutrition studies the 
idea of quality in addition to quantity which had 
heretofore seemed satisfactory to students of nutri- 
tion. Most proteins were found to be resolved into 
eighteen simple digestion products called amino- 
acids, and it was found that the proportions in which 
these were present in the protein molecule varied 
greatly in the proteins from different sources. All 
or nearly all of these digestion products appear to 
be indispensable constituents of an adequate diet. 
All natural foods contain several proteins as the 
extensive and valuable studies of Osborne have 
shown, ^ and although there are individual proteins 
which are entirely lacking in one or more of the essen- 
tial digestion products of proteins, every natural food 
appears to contaiu more or less of each of them. 
The proteins of any single food-stuff may be regarded 
as biologically complete, but their biological values 
differ greatly, depending upon the yield of the 
several amino-acids which can be obtained from 
them. 

Food Analysis. — Since proteins, carbohydrates, 
such as starches and sugars, fats and mineral salts 
came to be regarded as the essential constituents of 
the normal diet, it early became the principal activity 
of the investigator of nutrition problems to analyze 
foods of every sort by chemical methods in order to 



6 THE NEWER KNOWLEDGE OF NUTRITION 

determine their content of what were supposed to 
be the only essential food complexes. Pronounced 
differences were observed in the composition of the 
many substances which serve as food for man and 
animals.. Meats, milk, eggs, and a few seeds such 
as the pea and bean are very rich in protein, the 
cereal grains contain less of this food substance, 
whereas the tubers and vegetables, especially in the 
fresh condition, contain but very little. Equally 
great variations are observable in the water content 
of foods, and in their yields of fats and carbohydrates. 
One of the great epochs in the development of the 
science of nutrition, is tha,t in which Atwater and 
his associates examined and tabulated in classified 
form the chemical composition of an extensive list 
of human foods.' Following this, similar data were 
accumulated in the Agricultural Experiment Sta- 
tions concerning substances used for animal foods. 
Up to about 1900 the idea that there was any varia- 
tion in the quality of the proteins from different 
sources did not become generally appreciated. 

In the light of the revelations in the field of nutri- 
tion during the last few years, it seems remarkable 
that close studentg of animal nutrition accepted for 
so long, without proof, the behef that the results of a 
chemical analysis revealed the dietary values of 
food-stuffs. 

Disease and Diet. — ^Restricted diets of monotonous 
character have produced, for centurifes, diseases in 
man in several parts of the world. The only one 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 7 

of these which was at all general in the Western 
hemisphere was scurvy, a disease which caused much 
suffering among sailors in the days of the long sailing 
voyages. It was well understood that the disease 
was the sequel to the consumption of a faulty diet, 
composed usually of biscuit and salt meats, and that 
prompt recovery resulted from the consumption of 
liberal amoxmts of fresh vegetables and fruits. 
Decades passed without any systematic attempt to 
determine the cause of the peculiar value of this 
class of foods. 

Pellagra was a scourge among the poorest of peas- 
ants in parts of Europe for centuries, and its etiology 
has been referred by many to the poor quality of the 
simple and monotonous diet. This disease was not 
observed in America until after 1900. Since then 
it has been steadily increasing in the Southern States. 

Beri-beri is a disease common among the poorest 
classes of the Orient, who limit their food supply 
principally to polished rice and fish. It is remarkable 
that not until the year 1897 was the first fertile 
suggestion made by Eijkman,* as to the nature of 
the dietary fault which was responsible for the 
development of this disease. 

Man has been sufficiently industrious in most 
parts of the world to secure for himself a varied 
diet, derived from the cereal grains and legumes, 
fruits, roots and tubers, meats and certain leaves, 
which he found edible. Beginning with the dawn 
of the era of his most rapid advance toward achieve- 



8 THE NEWER KNOWLEDGE OF NUTRITION 

ment, he has in many parts of the world been the 
possessor and protector of flocks and herds, which 
provided him with clothing, and a constant supply 
of both meat and milk. The importance of this last 
item in his food supply we have just now come to 
really appreciate. It is in order that it may be fuUy 
appreciated how great are the differences in the 
nutritive value of foods of such a composition as to 
appear alike from the results of chemical analysis 
that the present account of the investigations of 
recent years was prepared. 

- In the year of 1907 the author began the study of 
nutrition problems at the Wisconsin Experiment 
Station. An inspection of the Uterature which re- 
lated to nutrition at that time disclosed the fact that 
the diet was supposed to consist essentially of pro- 
tein, carbohydrates and fats, and a suitable amount 
of several mineral salts. There were in the Uterature 
two papers which were highly suggestive that a new 
era was about to dawn in this field of research. 
Henriques and Hansen,^ believing that ghadin, one 
of the proteins of wheat, was free from the amino- 
acid lysine, had made up a diet of purified ghadin, 
carbohydrate, fats and mineral salts, and had at- 
tempted to nourish on this food mixture, animals 
whose growth was complete. It was reported, that 
rats had been kept in a state of nitrogen equihbrimn, 
and even retention of nitrogen (protein) was reported 
diu-ing an experimental period covering nearly a 
month. In most of their trials the animals failed 



BIOWDGICAL ANALYSIS OF FOOD-STUFF 9 

steadily from the time they were confined to food 
of this character. 

Willcock and Hopkins ' had conducted experiments 
with similar food mixtxires, composed of carefully 
purified food-stuffs in which all the constituents 
were known. When the protein of the diet consisted 
solely of zein, from maize, the mice Uved but a few 
days. When to this food the ajnino-acid trjrpto- 
phane, which is not obtained on the digestion of 
zein, was added to the diet, the animals hved dis- 
tinctly longer than without this addition. All ex- 
perimental work with such diets indicated that they 
were unable to support well-being in a young animal 
during growth over a prolonged period. It was an 
interest in these results, and a desire to know why 
such food naixtures, which compHed with all the re- 
quiremfents of the chemist and the dietitian, failed 
to properly nourish an animal that led to the decision 
that the study of nutrition offered a promising field 
of activity. 

At the Wisconsin Experiment Station there was in 
progress at that time an experiment which greatly 
strengthened the author's conviction that the most 
profitable point of attack for the study of the prob- 
lems of nutrition, lay in the study of greatly sim- 
plified diets so made up that every component should 
be known. It seemed that, employing such diets, 
and by the systematic addition of one or more purified 
substances known to be found in natural foods, or in 
animal tissues, it should be possible to arrive at the 



10 THE NEWER KNOWLEDGE OF NUTRITION 

solution of the problem of just what chemical com- 
plexes are necessary in the diet of the higher ani- 
mals. 

The above experiment was based upon earlier 
work by Professor S. M. Babcock, and was suggested 
by him, and carried out at first by Professors Hart 
arid Humphrey, and later with the cooperation of 
Mr. Steenbock and the author.'^ In this experiment 
the object was to determine whether rations, so made 
up as to be alike, in so far as could be determined by 
chemical analysis, but derived each from a single 
plant, would prove to be of the same value for growth 
and the maintenance of vigor in cattle. 

The ration employed for one group of animals was 
derived solely from the wheat plant, and consisted 
of wheat, wheat gluten and wheat straw; for a second 
group the ration consisted entirely of com plant 
products, and included the com kernel, com gluten, 
a by-product of the com starch industry, and the 
leaves and stalks of the com plant (com stover); 
the third group derived their ration solely from the 
oat plant, 'being fed entirely upon rolled oats and 
oat straw. There was a fourth group which it was 
supposed would serve as controls, which was fed a 
ration having the same chemical composition, but 
derived from about equal parts of wheat, com and 
oat products. 

The animals employed were young heifer calves . 
weighing about 350 pounds, and were as nearly 
comparable in size and vigor as could be secured. 



BIOLOGICAL ANALYSIS OF FOOD-STUFF H 

They were restricted absolutely to the experimental 
diets, and were well cared for. They were given all 
the salt (NaCl) they cared to eat, and were allowed 
to exercise in an open lot free from vegetation. Their 
behavior during growth, and in performing the f uno- 
tions of reproduction were extremely iateresting. 
AU groups ate practically the same amount of feed, 
and digestion tests showed that there was no dif- 
ference in the digestibility of the three rations. 

It was not until the animals had been confined to 
their experimental rations for a year or more that 
distinct differentiation ia their appearance was easily 
observable. The com fed group were sleek and fine 
and were evidently in an excellent state of nutrition. 
In marked contrast stood the wheat fed group. 
These animals were rough coated and gaunt in 
appearance and small of girth as compared with 
those fed the corn plant ration. The weights of 
the two groups did not differ ia a significant degree. 
The groups fed the oat plant ration and the mixture 
of the three plants, leaf and seed, stood intermediate 
between the two lots just described. The assimaption 
that the animals receiving the mixture of products 
would do better than any of the others, and thus 
serve as the standard group for controls was not 
reaUzed. The com fed anunals were at all times in 
a better state of nutrition than were those receiving 
the greater variety of food materials. 

The reproduction records of these animals are of 
special interest. The com fed heifers invariably 



12 THE NEWER KNOWLEDGE OF NUTRITION 

carried their young the full term, and the young 
showed remarkable vigor. All were normal in size 
and were able to stand and suck within an hour 
after birth as is the rule with vigorous calves. AU 
hved and developed in a normal manner. The young 
of the wheat fed mothers were the reverse in all 
respects. All were born three to four weeks too 
soon, and all were small and weighed on an average 
forty-six pounds, whereas the young of the corn fed 
animals weighed 73 to 75 pounds each. This weight 
is normal for new-born calves. The young were 
either dead when born or died within a few hours. 
The young of the mothers which had been grown on 
the oat plant were almost as large as those from the 
corn fed mothers, the average weight being 71 
pounds. AU of them produced their calves about 
two weeks too soon. One of the four was bom dead, 
two were very weak and died within a day or two 
after birth, the fourth was weak, but with care it 
was kept aUve. The young of the cows fed the 
mixture of the three plants were weak in most cases, 
and one was bom dead and one lived but six days. 
The mothers were kept on their experimental rations, 
and the following year they repeated in all essential 
details the reproduction records observed in the first 
gestation period. 

Records were kept of the milk production during 
the first thirty days of the first lactation period. The 
average production per day by each individual in 
the corn-fed lot was 24.03 pounds; for the wheat-fed 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 13 

animals 8.04 pounds, and for the oat-fed animals 
19.38 pounds. Those fed the mixture of the three 
plants produced 19.82 pounds of milk per cow per 
day during the first thirty days. In the second lacta- 
tion period the figures for milk production were 
28.0; 16.1; 30.1; 21.3 pounds, respectively, per day 
during the first thirty days. 

Through autopsy and analysis of tissues of the 
young, and analysis of the feces and urines of the 
animals in the several groups, an elaborate -attempt 
was made to solve the problem of the cause of the 
marked differentiation of the animals fed these 
restricted diets. Interesting data were secured 
which showed marked differences in the character 
of the fat in the nulk of cows from the different lots, 
and the observation was made that the tnines of the 
wheat fed animals were invariably distinctly acid 
in reaction, whereas those from the other lots were 
alkaline or neutral to litmus indicator. It was not 
possible by any means known to physiological chem- 
istry, to obtain a clue to the cause of the pronounced 
differences in the physiological well-being of the 
different lots of cows. This experiment confirmed 
the author's conviction that the only way in which 
the problems of nutrition could ever be solved, would 
be to solve the problem of the successful feeding of 
the most simplified diets possible. If this were 
accomplished it would be possible to proceed from 
the simple to the complex diets employed in prac- 
tical nutrition, ascertaining the nature of the dietary 



14 THE NEWER KNOWLEDGE OF NUTRITION 

faults in each of the natural foods, singly, the seed 
alone, and the leaf alone before attempting to inter- 
pret the cause of malnutrition in animals fed the 
more* complex mixtures. 

Such an undertaking as that just described, viz., 
the solution of the problem of why animals do not 
thrive on a diet of purified protein, starch, sugars, 
fats and inorganic salts which contained all the 
elements known to be left, as ash, on the incineration 
of an animal body, necessitated the employment of 
small laboratory animals. This was true for several 
reasons: First, because it is difficult and laborious 
to prepare isolated and purified food substances in 
sufficient amounts for the conduct of feeding experi- 
ments; second, it is both necessary and desirable to 
shorten the length of the experiments as much as 
possible, consistent with obtaining data regarding 
growth and reproduction, in order that data may 
accxmiulate sufficiently fast to make progress reason- 
ably rapid. The domestic rat seemed to be the most 
suitable animal, and accordingly it was selected. 
The rat has a gestation period of but 21 days, and 
the young are ready to wean at the age of 25 days. 
The female usually produces her first Utter of young 
at the age of about 120 days, and will as a rule have 
five Utters by the time she reaches the age of four- 
teen months, which age marks the end of her fertiUty. 
The span of life of a rat which is well nourished is 
about 36 months. When such an animal is employed, 
it is possible to accomplish within a relatively short 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 15 

time, the accumulation of data regarding growth 
and reproduction which it would take years to secure 
with domestic animals of large size, long period of 
gestation and long span of life. 

A sufficient nmnber of comparable experiments 
have now been conducted with several species of 
animals to make it appear certain that the chemical 
requirements of one species are the same as that of 
another among all the higher animals. The require- 
ments with respect to the physical properties of the 
food vary greatly. The ruminants must have bulky 
food with the right consistency, whereas the omnivora 
(man, pig, rat, etc.), cannot, because of the nature 
of their digestive tracts, consume enough of such 
foods as leaves and coarse vegetables, to meet their 
energy requirements. 

The early efforts to noiirish young rats on diets 
composed of purified proteins, carbohydrates, fats 
and mineral salts, confirmed the results of the earlier 
investigators. The animals hved no longer on such 
food mixtures, than when allowed to fast. The 
rations employed were of such a character that the 
most thorough chemical analysis could reveal no 
reason why they should not adequately nourish an 
animal. It seemed obvious that there was some- 
thing lacking from such mixtures which is indis- 
pensable for the nutrition of an animal, and a system- 
atic effort was made during the years that followed 
to discover the cause of failure of animals to develop 
on diets of purified and isolated food-stuffs. It was 



u^ 



1 1 



16 THE NEWER KNOWLEDGE OF NUTRITION 

not until 1912 that light began to be shed upon the 
problem. 

The diet which was most in use at that time con- 
sisted of purified casein to the extent of about 18 
per cent, lactose 20 per cent (supposed to be pure), 
about 5 per cent of some fat, together with a salt 
mixture which was made up in imitation of the min- 
eral content of milk, and the remainder of starch to 
make 100 per cent.* This food mixture was sup- 
posed to be comiposed of materials sufficiently pure 
to comply with the requirements of such work; 
that is, they were supposed to contain too Uttle of 
any impm-ities which would in any way influence 
the results. With this diet the interesting observa- 
tion was made that growth could be secured when the 
fat in the food mixture was butter fat, whereas no growth 
could be secured when the butter fat was replaced by 
lard, olive oil or other vegetable oils. Egg yolk fats 
were next tried and were found to induce growth in 
the same manner as butter fat. It was definitely 
estabhshed that, contrary to the past beliefs, the 
fats are not all of the same dietary value. Certain 
fats contain some substance which is not dispensable 
from the diet, whereas other fats do not contain the 
dietary essential in question. 

The portion of the food mixture other than fat, 
appeared to contain only substances of known com- 
position, i. e., protein, carbohydrate and inorganic 
salts, and for a time it appeared thai the imknown 
substance in butter fat was the only element of 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 17 

mystery in the diet. The lactose or milk sugar was 
carefully examined as to its purity and was judged 
to be sufficiently pure to be satisfactory for such 
experimental work, since it was practically free from 
nitrogen. The tentative conclusion was reached 
that the essential factors in an adequate diet included 
one substance or a group of substances which had 
not been appreciated in the past, and that these, 
if there should be more than one, were associated 
with certain fats but not with all. 

This observation was in harmony with the pub- 
lished work of Stepp ' which had appeared in 1909. 
Stepp observed that grown mice were satisfactorily 
nourished by a bread which was made with milk, 
but that early failure and death followed when the 
aninials were fed the same bread which had been 
previously extracted with alcohol. When the sub- 
stances extracted from the bread by alcohol were 
replaced, the bread was again rendered efficient for 
the maintenance of hfe and health. He demonstrated 
in other experiments that the bread could be ex- 
tracted with ether or with chloroform without re- 
moving the substance which was soluble in alcohol,* 
and without which the animals steadily failed. 
Stepp considered the unknown substance or sub- 
stances with which he was dealing in his feeding work, 
as belonging to the not well defined group of sub- 
stances generally called lipoids. This group includes 
fats and related substances more complex in char- 
acter, some of which contain the elements, phos- 



18 THE NEWER KNOWLEDGE OF NUTRITION 

phorous and nitrogen. Stepp was not able to secure 
with any known- lipoid, the effects which resulted 
from the administration of the alcohol-soluble por- 
tion of his milk bread. 

A new viewpoiat was suggested by F. G, Hopkins 
of Cambridge, England, in 1912.^° He had as early 
as 1906- conducted experiments in the feeding of mix- 
tures of purified protein, carbohydrate, fats, and 
mineral salts and was aware of the fact that neither 
maintenance of body weight, nor growth could be 
secured with such diets. He then tried the addition 
of such amounts of milk as would furnish 4 per cent 
of the total dry master of the food mixture and ob- 
served that growth could proceed when such milk 
additions were made. Hopkins suggested the exist- 
ence of certain unidentified food substances which 
were supplied by the milk and to these he gave the 
name "accessory" articles of the diet. 

Attention has been called to the fact that Eijk- 
man, a student of the disease, beri-beri, made the 
discovery in 1_897 that pigeons fed solely upon pol- 
ished rice, develop usually within three or foiu- weeks, 
a state of paralysis which is called polyneuritis, and 
is analogous to beri-beri in man. He found that 
when the birds were given the entire rice kernel, or 
unpolished rice the disease did not develop. It was 
found, furthermore, that the administration of rice pol- 
ishings to pigeons suffering from polyneuritis, caused 
prompt rehef of their symptoms. Eijkman's ob- 
servations attracted little attention until 1911, when 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 19 

Funk took up the study of beri-beri, and made an 
ekborate attempt to isolate and study the " curative " 
substance in rice poUshiags." Fraser and Stanton 
had, however, in 1907, employed alcohoHc extracts 
of rice polishings for the relief of experimental 
poljmexuitis.^^ In the work of these investigators 
the erroneous . assumption seems to have prevailed 
that the process of pohshing consists essentially of 
the removal of the outer covering, or bran layer of 
the rice kernel. As a matter of fact the rice germ 
is in a very exposed position, and is easily rubbed 
off during the process of pohshing. As was later 
shown by McCoUum and Davis, for the wheat 
kernel, the germ is a very different thing from the 
seed from the dietary standpoint.^' The reason for 
this will be made clear later. 

The studies of Eijkman, Hopkins, Fraser and 
Stanton and Funk, .referred to above, clearly sug- 
gested that there was required in the diet something 
other than protein, carbohydrate, fats and inorganic 
salts. When McCoUum and Davis succeeded in 
securing growth in young rats fed upon a mixture of 
"purified" food-stuffs, when the mixture contained 
butter fat, but no growth when vegetable fats or 
the body fats of animals were substituted, it appeared 
to them that the only element of mystery in the diet 
was that associated with certain fats. This could 
not at first be harmonized with the observation of 
Funk, namely, that butter fat had no favorable 
influence on pigeons which were suffering from ex- 



20 THE NEWER KNOWLEDGE OF NUTRITION 

perimental beri-beri." His studies seemed to in- 
dicate that there is necessary in the normal diet at 
least one other substance, the absence of which 
brought on the attack of polyiieuritis. Later experi- 
ments by McCoUum and Davis cleared up the prob- 
lem, but not without a considerable amount of 
experimenting and delay. 

McCoUum and Davis arrived at the conclusion 
that aside from the long recognized constituents of 
the norma,l diet, there is some unknown substance in 
butter fat which must likewise be furnished in the 
food, and began a systematic investigation of the 
problem of why a young animal cannot grow when 
restricted to a single grain such as wheat, maize 
(com), oats, peas, beans, etc. They had tried many 
times to limit young rats to whole wheat, or other 
grain as their sole food, and had found that they 
not only failed to grow, but would not live many 
weeks. Chemical analysis shows the cereal grains 
to contain all the essential food substances, for which 
we know how to analyze, viz: proteins, starch, sugar,, 
fats and all the mineral salts which occur in the body 
of an animal. 

It was reasoned that, since all the dietary essen- 
tials, except possibly the one which is not present in 
vegetable fats, are certainly present in the wheat 
kernel, the faults in the latter must depend upon a 
lack of the unknown substance contained in butter 
fat, or on the quality of some one or more of the well 
recognized constituents of the diet. It seemed 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 21 

)ssible to discover by means of a systematic series 
feeding experiments in which the quality of the 
ed should be improved with respect to one dietary 
ctor at a time, which factor was interfering with 
owth. Accordingly they fed wheat in the following 
mbinations, and with the results noted: 

I Wheat alone no growth, short life. 

I Wheat plus purified protein no gro'veth, short life. 

I Wheat plus a salt mixture which gave it a mineral content 

similar to that of milk very Uttle growth. 

Wheat plus a growth promoting fat (butter-fat) 

no growth. 

From these results it seemed apparent that either 
eir working hypothesis regarding the factors which 
B necessary in an adequate diet, must be wrong, 

there must be more than a single dietary factor 
poor quality, and jointly responsible for the poor 
Mtion of the animals. In order to test this theory 
ey carried out another series of feeding experiments, 

which wheat was fed, supplemented with two 
irified food additions. 

Wheat plus protein, plus the salt mixture Good 

growth for a time. Few 
or no young. Short life. 
Wheat plus protein, plus a growth-promoting fat (butter- 
fat) No growth. Short life. 

Wheat plus the salt mixture, plus the growth-promoting fat, 

(butter-fat) Fair growth for a time. Few 

or no young. Short Ufe. 



22 THE NEWER KNOWLEDGE OF NUTRITION 

The behavior of the animals fed wheat with two 
purified food additions was highly suggestive that 
there are three dietary factors of poor quaUty in 
the wheat kernel. This was demonstrated to be 
true by a feeding trial in which wheat was fed with 
three purified food additions: 

(8) Wheat plus protein, plus the salt mixture, plus a growth- 
promoting fat (butter-fat) .... Good growth, normal 

number of young, good 
success in rearing young ; 
life approximately the 
normal span. 

McCoUum and Davis were, in 1912, more than 
ever convinced that the only element of mystery, in 
the normal diet was the unidentified substance in 
butter fat, for with the improvement of three dietary 
factors wheat became a satisfactory food for the 
nutrition of an animal during growth and for the 
support of all the functions of reproduction and 
rearing of young. 

This series of experiments brought to light two 
new viewpoints in animal nutrition, one of which was, 
that the inorganic content of the wheat kernel, although 
it furnishes all the necessary elements, does not contain 
enough of certain of these to meet the requirements of a 
young animal during the growing period. It is true 
that some years earlier Henry," had called at- 
tention to the deficiency of the corn kernel in ash 
constituents, and had in some of his experiments 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 23 

added wood ashes to the diet, with noticeable im- 
provement in the well-being of the animals. The 
fact that seeds such as wheat fail to supply enough 
of any of the essential inorganic elements was not 
generally appreciated and was given but httle at- 
tention in works on nutrition. Later, work by Mc- 
CoUum and Simmonds, demonstrated that the de- 
ficiency in mineral elements in wheat and other 
seeds is limited to three elements, calcina, sodium 
and chlorine. 

A second new viewpoint brought out by these ex- 
periments was the fact that the wheat kernel is indeed 
too poor in its content of the unidentified substance 
which butter fat contains, to satisfactorily nourish an 
animal over a long period of time. 

It has already been mentioned that the studies of 
Kossel, Fischer and of Osborne, had made it clear 
that there should exist very pronounced differences 
in the value of the proteins from different sources. 
The proteins were prepared in a state of relative 
purity and were digested in the laboratory by means 
of acids, and were analyzed by the methods of 
Fischer and of Kossel. Certain of the eighteen di- 
gestion products, the amino-acids, were determined 
quantitatively so far as the methods would permit. 
Although the methods were never perfected so as to 
give results which were approximately quantitative, 
except in the case of less than a third of the amino- 
acids which were known to be formed in the di- 
gestion of proteins, it was shown In the case of these 



24 THE NEWER KNOWLEDGE OF NUTRITION 

few that there were very great variations in the pro- 
portions among them in the mixture obtained from 
proteins from different sources. Thus the proteins 
of the muscle tissues of several species of animals 
were shown to yield between 12 and 14 per cent of 
glutamic acid, one of the digestion products obtained 
efrom practically all proteins. The same amino-acid 
is present in the two principal proteins of the wheat 
kernel to the extent of about 40 per cent of the 
total protein. These two proteins together make 
about 85 per cent of the total protein of the wheat 
kernel. Other equally great differences were shown 
to exist in the composition of proteins of our common 
food-stuffs and those of the tissue proteins which 
are formed during growth. 

A good illustration of the problems which the 
animal meets in its protein nutrition, may be had by 
comparing the digestion products of the protein 
molecule to the letters of the alphabet. The pro- 
teins of the food and of the tissues are made up 
of the same letters arranged in different- orders and 
.present in different proportions. In growth the 
animal takes as food; proteins which are very unlike 
those of its tissues, digests these into the simple com- 
plexes, the amino-acids, and then, after absorbing 
these, puts together the fragments in new order, 
and in new proportions to form the tissue proteins. 

If the muscle tissue of an animal be likened to a 
block of printer's type so arranged as to print the 
rhyme beginning "Jack Spratt, who could eat no 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 25 

fat, and his wife could eat no lean," the proteins of 
which the muscle consists are represented by the 
individual words, and the digestion products of the 
proteins by the letters of which the words consist. 
Now if the animal could take in its food proteins 
which correspond to a block of type which would 
print the jingle beginning: "Peter Piper picked a 
peck of pickled peppers," it is easy to understand 
that when the proteins of the food are resolved to 
their constituent letters, and an effort made to form 
the body proteins of the new and different type 
from the letters suppUed by the food, the trans- 
formation cannot be made. In setting up the first 
Une, "Jack Spratt could eat no fat and his wife 
could eat no lean," we need four of the letter t, but 
the food proteins contain but one. The first line of 
the Jack Spratt rhyme, which represents the muscle 
proteins, requires but one letter p, whereas the food 
proteins represented by the Peter Piper rhyme 
yield nine in the first Une. The first line of the 
Jack Spratt rhyme contains the letters j and n, 
whereas the Peter Piper rhyme contains none, so 
that even with the entire stanza: 

Peter Piper picked a peck of pickled peppers 
If Peter Piper picked a peck of pickled peppers, 
Where's the peck of pickled peppers, 
That Peter Piper picked? 

it is not possible to reproduce even the first hne of 
the Jack Spratt rhyme, and in order that growth 



26 THE NEWER KNOWLEDGE OF NUTRITION 

might become possible, it would be necessary to 
take proteins of another character, which would 
supply the missing letters. 

Such a comparison between food proteins and 
tissue proteins gives a good illustration of the kind 
of problem which the animal meets in its protein 
iiutrition. The most conspicuous protein of the com 
kernel (zein) is wholly lacking in three of the amino- 
acids or digestion products which are obtainable 
from most tissue proteins. In accord with what we 
should expect on theoretical grounds, this protein 
is, when taken as the sole source of amino-acids, not 
capable of supporting growth, or of mAintaiaing an 
animal in body weight^i This illustration shows how 
we may have excellent, good or poor food proteias 
for the formation of body proteias in growth. 

The investigations described above, the object of 
which was to find the cause of the failure of an 
animal to grow when restricted to wheat as its sole 
source of nutriment, were carried out in 1912, the 
year following the publication of the first work by 
Funk on polyneuritis. In the same year Hop- 
kins called attention to the remarkable effects pro- 
duced by the addition of small amounts of milk to 
diets composed of piirified food-stuffs. The "vita- 
mine" hypothesis had just been formulated by 
Funk." McCollumand Davis were, therefore, aware 
of the relation of a diet of polished rice to experi- 
mental beri-beri. They believed, in the light of 
their experiences with the diet of purified protein, 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 27 

carbohydrate, fats and inorganic salts, which, they 
observed, was capable of inducing growth when cer- 
tain fats were supplied, but not when others were 
substituted, and the further fact that wheat could 
be supplemented by purified protein, a growth- 
promoting fat, and a suitable salt mixture, i. e. with 
food-stuffs of known character, that there was but 
a single tmidentified substance necessary in the diet. 
They decided to next apply to polished rice the 
same procedure which hB,d shown so clearly the 
nature of the dietary deficiencies of wheat. Rice, 
they reasoned, could be nothing less than a mixture 
of proteins, starch, traces of faf, and a mixture of 
inorganic salts, similar to that contained in wheat, 
but smaller in amount. It should, therefore, be 
supplemented with a suitable salt mixture, a purified 
protein, and a growth-promoting fat, so as to in- 
duce growth and maintain animals for a long time 
in a state of health. This seemed to be a necessary 
conclusion, since they had secured growth and well- 
being in animals fed strictly upon a mixture of puri- 
fied protein (casein), starch, milk-sugar, butter fat 
and a mixture of inorganic salts of suitable com- 
position. 

it was a great surprise to McCollum and Davis 
to find that polished rice, even when supplemented 
with the purified protein, casein, butter fat and a 
salt mixture properly constituted, failed utterly to 
induce any growth in young rats." Not only did 
they fail to grow, but in the course of a few weeks 



28 THE NEWER KNOWLEDGE OF NUTRITION 

they developed in some cases a state of paralysis 
which was suggestive of polyneuritis. Here was an 
apparent contradiction. The polished rice could be 
nothing less than a mixture of protein, carbohydrate 
and salts. The only difference between this and the 
mixture of supposedly purified food-stuffs with which 
they had achieved success was in the 20 per cent of 
milk sugar which the latter contained. It was, 
therefore, decided to repeat the experiments with 
the latter mixture, with the milk sugar replaced by 
starch. It was found that this change in the com- 
position of the food mixture made the difference be- 
tween success and "failure. No growth could be se- 
cured when the mUk sugar was omitted. Later 
experiments showed that if milk sugar was suf- 
ficiently purified by repeated crystalUzation it was 
no longer effective in inducing growth when added 
to the purified food mixture, whereas the water from 
which the sugar had been crystallized would, when 
evaporated upon the food mixture, render it capable 
of inducing growth. This made it evident that there 
is indeed a second dietary essential, of which an 
animal needs but a very small amount, but which 
is absolutely necessary for both growth in the young 
and the maintenance of health in the adult. 

Further experiments were then conducted to find 
whether this unidentified substance which was being 
added accidentally as an impurity in'the milk sugar, 
was the same as the substance which Eraser and 
Stanton and Funk were dealing with in their studies 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 29 

of beri-beri. It was found that pigeons which had 
developed beri-beri as the result of being fed ex- 
clusively upon polished rice, could be temporarily 
"cured" with any preparation which would, when 
added to the diet of purified food-stuffs, containing 
a growth-promoting fat, cause animals to grow. 

Following the method introduced by Fraser and 
Stanton, McCollum and Davis, ^* next employed 
alcoholic extracts of various natural foods, adding 
the alcohol, soluble matter to the standard mixture 
of purified protein (casein), starch (dextrinized), 
salts and butter fat, and soon became convinced 
that the substance which relieves the condition of 
polyneuritis in pigeons was always present in the 
preparations which render the purified food mixture 
capable of promoting growth. They finally adopted 
an alcoholic extract of wheat germ as a source of 
this dietary factor in their investigations. Funk 
and his co-workers had previously shown that^;'-^^ 
curative substance is present in many i-^n^ 
foods. '^ Repeated trials showed that the inclusiiON. 
of the alcohoUc extract of wheat germ or of othei \ 
food, was not sufficient to induce growth unless 
the butter fat was likewise added to the purified food 
mixture. Both the growth-promoting fat and the 
trace of unidentified substance in the alcoholic extract 
of wheat germ are necessary for the promotion of 
growth or the preservation of health. 

It has been pointed out that Fimk, in his examina- 
tion of the various natural foods for the purpose of 



30 THE NEWER KNOWLEDGE OF NUTRITION 

determining the distribution of the antineuritic sub- 
stance (substance which relieves polyneuritis) found 
butter fat ineffective. This was later confirmed by 
McCollum and Kennedy." 

Through the "vitamine" hypothesis, Funk at- 
tempted to account for the diseases beri-beri, scurvy, 
pellagra and rickets, as being each due to the lack 
of a specific chemical substance, a "vitamine," in 
the diet.^^ This was a very logical conclusion from 
the data available to Fimk. Scurvy, it had long 
been known is relieved in a very spectacular manner 
by the inclusion of fresh vegetables or orange juice 
in the diet, and there was no doubt that the disease 
developed as the result of a diet of poor quality. On 
Brst consideration it seemed very reasonable to 
assume that there is an "antiscorbutic vitamine" 
in certain fruits and vegetables. 
Pellagra has long been suspected of being due to 
"Ib^ diet, although the exact maimer in which the 
^^_„-iiS unsatisfactoiy remained obscure. It was 
g&nerally appreciated by clinicians that a change to 
a, highly nutritious diet in_ which milk and eggs were 
jonspicuous was the best prophylactic measure for 
[;he treatment of the disease, and that without diet- 
ary measures, all remedies fail. It was not surpris- 
ing that Funk should have regarded pellagia as one 
jf the "deficiency" diseases, due to lack of a "vita- 
nine" ia. the diet. As will be shown later (Chapter V) 
lihere has since been secured much experimental evi- 
dence in support of the view that scurvy and pellagra 



BIOLOGICAL ANALYSIS OP FOOD-STUFF 31 

do not arisfe from deficiency in the diet of specific 
chemical substances in the sense in which Funk 
suggested. This seems to be true also of rickets. 
In view of the considerations just mentioned rel- 
ative to the cause of scurvy and pellagra, and the 
convincing evidence that beri-beri is actually caused 
by specific starvation for a substance, "vitamine," 
as Funk suggested, McCollmn and Davis formulated 
in the following way, their working hypothesis as to 
what constitutes an adequate diet. The diet must 
contain, in addition to the long recognized dietary 
factors, viz: protein, a source of energy in the form 
of proteins, carbohydrates and fats; a suitable supply 
of certain inorganic salts, two as yet unidentified 
substances or groups of substances.** One of these 
is associated with certain fats, and~is especially 
abundant in butter fat, egg yolk fats and the fats 
of the glandular organs such as the fiver and kidney, 
but is not found in any fats or oils of vegetable oriT 
The second substance or group of substaaQj*v 
chemically imidentified nature, is never as^ocia\ > 
with fats or oils of either animal or vegetable origin. 
It is widely distributed in natural foods, and can be 
isolated in a concentrated, but not in a pure form, 
from natural food-stuffs by extraction of the latter 
with either water or alcohol. This water or alcohofic 
extract always contains the substance which cures 
polyneiuitis. At the time it seemed possible that 
it also contained several other "vitamines," pro- 
tective agaiost the other diseases mentioned. The 



32 THE NEWER KNOWLEDGE OF NUTRITION 

former substance or group of substances, which is 
associated with certain fats is not "curative" for 
any of the list of diseases which Funk designated as 
"vitamine" deficiency diseases. Indeed, butter fat, 
which is the food containing one of the indispensable 
substances in greatest abimdance, was stated by 
Funk to contain no "vitamine." " 

Nomenclature of the Unidentified Dietary Essen- 
tials. — ^The ending amine has a definite and specific 
meaning in organic chemistry, and appUes only to 
substances containing the element nitrogen. Since 
butter fat, which is very rich in one of the dietary 
essentials in question is practically, if not entirely, 
free from nitrogen, it seems almost certain that the 
physiologically indispensable substance which it con- 
tains is free from nitrogen, and could not with pror 
priety be designated by any name ending in amine. 
For this reason, and because it is possible to divide 
'''^.unidentified constituents of the normal diet into 
^ji-wasses on the basis of their solubiUty, McCoUum 
stnd Kennedy " proposed the terms fat-soluble A 
and water-soluble B to designate them. The former 
prevents the development of a pathological condition 
of the eyes,^" the latter prevents the development of 
beri-beri. As will be shown later, there is much 
evidence for and none against the vieW that what we 
designate by each of these terms is in reality but a* 
single physiologically indispensable substance and 
not a group of substances. This necessitates the 
further assumption that certain of the diseases of 



BIOLOGICAL ANALYSIS OF FOOD-STUFF 33 

dietary origin, wHich Funk held to be due to "vi- 
tamine" starvation, are in reality due to other causes. 
This view will be supported by further evidence later. 
Indeed it is not possible to longer regard scurvy as 
a "vitamirie" deficiency disease. 

The "vitaooaine" hypothesis of Funk was extremely 
attractive and seemed to account for the etiology 
of several diseases ia a most satisfactory way. It 
seemed to rest upon sound observations, but in 
reaUty it rested only upon suggestive chemical ev- 
idence. It failed to stand the test of a systematic 
investigation of all the more important natiu-al 
food-stuffs, by the biological method which was 
described in its essential features in illustrating the 
nature of the dietary deficiencies of the wheat kernel. 



CHAPTER II 

EXPERIMENTAL SCtJUVY AND THE DIETARY PROPERTIES 
OF VEGETABLES 

McCoUum, Simmonds and Pitz ^ sought to test 
the validity of the "vitamine" hypothesis in its 
relation to scurvy, by an indirect method. The next 
logical step in the investigation of the possible num- 
ber of dietary essentials of unknown chemical nature 
which occur in the growth-promoting fats (fat-' 
soluble A), and in the preparations which are never 
associated with fats (water-soluble B), seemed to be 
to study the oat kernel. There seemed much reason 
to beheve that this seed would prove to be unique 
among the ordinary seeds in its dietary properties. 
Theobald Smith ^ had, in 1895, called attention to the 
fact that a diet of oats would cause in guinea pigs 
the development of a condition suggestive of scurvy. 
In 1909 Hoist and his co-workers in Sweden ' de- 
scribed numerous experiments involving the produc- 
tion and relief of experimental scurvy in the guinea 
pig. Hoist observed that when this animal is re- 
stricted to a diet of oats it rarely fails to develop 
scurvy within a few weeks. The disease which is so 
produced is strikingly suggestive of scurvy in man. 
There is pronounced swelling of the knee and elbow 
joints, with rupture of the capillaries at these sites, 

34 



DIETARY PROPERTIES OF VEGETABLES 35 

and there is also a spongy and hemorrhagic condition 
of the gums. 

Hoist stated that the disease was due to a deficiency 
of the oat kernel in an antiscorbutic substance, which 
is relatively unstable when manipulated in the lab- 
oratory. Milk was stated to be efl&cient for the cure 
of the disease induced by an oat diet, provided it was 
raw or had not been heated to very high tempera- 
tures. Milk which had been heated to 90° C. for 
ten minutes was said to be still effective, but boiled 
nulk failed to induce a cure. Raw cabbage was 
stated to be highly efficient as a remedy against 
the disease in the guinea pig, whereas cooked or 
dried cabbage had lost most of its antiscorbutic 
property. 

In view of these observations, it seemed that, if 
it were true that scurvy is as Fimk and Hoist be- 
lieved, a disease resulting from "vitamine" defi- 
ciency, the oat kernel should prove to be a natural 
-food-stuff which lacked the antiscorbutic "vitamine" 
but contained the anti-beri-beri, and perhaps, also, 
the anti-pellagra and other ' ' vitamines. ' ' McCollum, 
Sipamonds and Pitz^ submitted the oat kernel to the 
systematic procedure of the biological method of 
analysis, feeding it as the sole source of nutriment, 
and also with single and multiple additions of purified 
food substances, employing the rat as the experi- 
mental antoaal. This showed that the oat kernel 
(rolled oats) can be supplemented by the addition of 
a salt mixture of appropriate composition, a growth- 



36 THE NEWER KNOWLEDGE OF NUTRITION 

promoting fat, and the purified protein gelatin, so as 
to induce growth at the maximum rate in young rats 
from weaning time to the full adult size, and sup- 
ported the production of a few young. When any 
one of these additions is omitted, the animals fail to 
develop. 

The oat kernel, therefore, contains all the dietary 
essentials in the water-soluble group (provided there 
is more than one such substance). Like wheat it 
lacks a sufficient amount of the fat-soluble A to 
support normal nutrition. It was impossible to 
harmonize the results described by Hoist in the 
production of experimental scurvy in the guinea pig 
with those of McCoUum, Simmonds and Pitz, in 
which the rat" served as the experimental animal, 
without making assumptions which would greatly 
compUcate the whole subject of nutrition investiga- 
tions. There were serious discrepancies in the ex- 
perimental data from different sources. Hoist's 
studies pointed to the existence in the normal diet, 
of a substance or substances of unknown character, 
which were easily destroyed by heat or by dessica- 
tion, and which act as protective agents against 
scurvy in the guinea pig, and appeared to demon- 
strate that the supposed antiscorbutic substance or 
substances were absent from the oat kernel. The 
studies with the rat demonstrated beyond con- 
troversy, that at least for the rat, the oat kernel is 
deficient as a food only as respects the factors, in- 
organic salts, fat-soluble A, and in a lesser degree in 



DIETARY PROPERTIES OF VEGETABLES 37 

the quality of its protein. When these factors are 
corrected, the oat kernel becomes a complete food 
for this species. 

Scurvy has been produced experimentally by 
faulty diet in the guinea pig, and is not known to 
occur in any species other than man and the guiaea 
pig. If the explanation of Hoist and of Funk is cor- 
rect that scurvy is the result of the lack of a specific 
substance in the diet, it becomes necessary to make 
the further assiunption that man and the guinea pig 
require this substance, sLuce both suffer from the 
disease, whereas other species, as the rat, do not re- 
quire this complex as a dietary component. The 
only alternative is to conclude that scurvy is in 
realty not a "deficiency" disease in the sense in 
which Funk and Hoist employed the term. That 
there is actually no such unstable "antiscorbutic 
substance" or "antiscorbutic vitamine" as postu- 
lated by Hoist and Funk, has been demonstrated by 
the studies of McCoUum and Pitz.* The proof of 
this is given in Chapter V. In the same chapter will 
be discussed the other so-called "vitamine" deficiency 
diseases, pellagra and rickets, and the character of 
the diets which play a part in their etiology. The 
data available supports the view that among the list 
of so-called "deficiency" diseases, beri-beri, scurvy, 
pellagra and rickets, only the first is due to the lack 
of a specific protective substance, Funk's "vitamine," 
or watei^soluble B in the diet. The others are at 
least in some degree the result of faulty diets, but not 



38 THE NEWER KNOWLEDGE OF NUTRITION 

in the sense in which Funk and Hoist employed the 
term "deficiency." McCoUum and Simmonds have 
pointed out, however, that in the pathological con- 
dition of the eyes, known as xerophthalmia, of dietary 
origin mentioned above, we have a second deficiency 
disease, analogous to beri-beri.^ All the facts- at 
present available point, therefore, to the belief that 
what MeCoUum and his co-workers term water- 
soluble B, is in reality but a single physiologically 
indispensable substance.^ There is no evidence in 
support of the view that the term fat-soluble A need 
be considered as applying to more than a single 
chemical substance. Xeropthalmia of dietary origin 
will be described later (Chapter V). 

•Similarity of the Seeds from the Dietary Standpomt. 
— ^By the apphcation of the biological method 
of analysis of a food-stuff to each of the more im- 
portant seeds employed in the nutrition of man and 
animals, the fact was brought to fight that they all 
resemble each other very closely in their dietary 
properties. The Ust of seeds, examined included, — 
wheat,'^ corn,^ rice," rolled oats, rye,' barley,' kafiir 
com,' naillet seed,^" flaxseed,^" pea^" and both the 
navy" and the soy bean.' These all contain proteins 
which are of distinctly lower biological value for 
growth than are the proteins of milk; they all are too 
poor in the same three inorganic elements, calcium, 
sodiimi and chlorine. All are, with the exception of 
millet seed, below the optimiun in their content of 
the dietary factor, fat-soluble A. These three diet- 



DIETARY PROPERTIES OF VEGETABLES 39 

ary factors must be improved before any one of these 
seeds becomes complete from the dietary stand- 
point. The seeds are, therefore, to be classed to- 
gether as regards their food values. 

Since the seeds have the same faults from the diet- 
ary standpoint, it is to be expected that when fed in 
mixtures they should not supplement each other ex- 
cept as regards the protein moiety. It would hardly 
be expected that the proteins of two or more kinds 
of seeds should be deficient in the same amino-acids, 
and in the same degree, and feeding trials have shown 
that mixtures of seeds furnish better protein values 
for growth than do the single seeds when fed alone, 
properly supplemented with respect to all other 
factors. From the similarity of the inorganic con- 
tent of all seeds, and their low content of the fat- 
soluble A, it should be necessary to supplement any 
mixture of seeds with respect to both these factors 
before good nutrition can be secured. Experimental 
trial shows this to be the case. It is not, therefore, 
possible to secure appreciable growth in young animals 
fed exclusively upon seed products as the sole source of 
nutriment. 

Casual observation teaches us that such animals 
as the ox, horse, sheep and goat can grow and live 
for years in a vigorous condition on diets derived 
entirely from vegetable sources. After having un- 
successfully attempted numerous times to induce 
growth in animals fed strictly upon seed mixtures, 
the thought naturally arose that there must be some 



40 THE NEWER KNOWLEDGE OF NUTRITION 

• 

s|)ecial properties in the leaves of the plant which 
cause them to make good the dietary deficiencies of 
the seeds. A careful inquiry in every possible direc- 
tion failed to discover any animal which in its natu- 
ral state limits its diet strictly to seeds. Birds all 
appear to vary their diet of seeds witji insects and 
worms, and most birds eat to some extent of fruits 
and certain tender leaves. All birds probably eat a 
considerable amount of mineral substance in the 
form of particles which they deliberately swallow, 
and they secure in their natural state more or less of 
all of the essential mineral elements in the drinking 
water whigh has permeated the ground. These sup- 
plemental sources of certain food substances, which 
one is at first inclined to overlook, or if considered,, 
to regard as of an accessory nature, and therefore, 
if "accessory," dispensable, are in reality of such 
importance, that it is not too much to say that the 
preservation of the species might turn upon the 
opportunity or lack of opportunity to secure these 
substances. 

Among the onmivora, the author has been unable 
to discover any species which subsists entirely upon 
seeds. The hog is a typical omniverous feeder, but 
it is well known to animal husbandrymen that there 
are but two successful methods of pork production, 
one of which is to feed growing pigs on grain while 
they have access to a good pasture; the other is to 
feed them milk, skim milk, or butter-milk, along 
with a grain mixture. Ignorance of this fact has re- 



&^ 



DIETARY PROPERTIES OF VEGETABLES 41 

suited in enormous economic loss to farmers who 
have attempted tor keep growing pigs in a dry lot 
and feed them cereal grains and by-products derived 
from these, as. the sole source of nutriment. Little 
growth can be secured under these circumstances, 
and the reason becomes clear from what has been 
said above concerning the nature of the dietary- 
deficiencies of the seeds and the similarity of the 
seeds froin the dietary standpoint.* 

It was a great surpriseto McCoUum, Sinunonds 
and Pitz '^ to find that appropriate mixtures of leaf 
and seed make fairly satisfactory food mixtures for 
the support of growth, whereas, as has been stated, 
they were unable to secure any appreciable growth 
in animals fed exclusively on seeds and seed products, 
the drinking water suppHed being distilled and there- 
fore salt free. The first leaf which was studied was 
that of the alfalfa plant, for the reason that the 
ground, immature alfalfa plant is extensively mar- 
keted as a supplementaiy feed for pigs, and through 
the courtesy of the Peters MUUng Company of 
Omaha, Nebraska a product "alfalfa flour" was 
made available in a convenient form. This consists 

* It is not to be understood from this that it is intended to imply 
that no increase in body weight can be secm^ed in hogs when they are 
confined strictly to grain mixtures. They may indeed become very 
fat, and therefore apparently grow for a time on such foods as corn 
alone. Even under farm conditions, where they are able to secure 
a supplementary mineral supply through the water they drink and 
through the consumption of soil with the grain, there is little growth 
in the sense that the muscle and organ tissues increase in volume. 



42 THE NEWER KNOWLEDGE OF NUTRITION 

of the dry, iimnature leaf of the plant ground to a 
very fine powder of a bright gre^n color. 

A series of diets consisting of seed, 60 per cent, 
and of aKaKa leaf flour, 40 per cent, were first 
fed to growing rats. The seeds employed, included 
wheat, com, rolled oat, rye, millet seed, kafiir com,, 
pea and bean. The degree of success in inducing 
growth with most of these simple naixtures of one 
seed with the alfalfa leaf is njuch greater than can ever 
be secured with even such complex mixtures of seeds 
as com, wheat, oat, henip seed and irdllet seed in 
equal proportions. The latter mixture can support 
a fair amount of growth when its inorganic defi- 
ciencies are made good, but without mineral addi- 
tions almost no growth can be secured. Chart 6 
shows typical growth curves which give an accurate 
idea of the relative values for growth of several 
combinations of the alfalfa leaf with seeds. Among 
the seeds with which studies have been made, the 
oat is best supplemented by the alfalfa leaf. A 
simple mixture of roUed oats, 60 per cent, and alfalfa 
leaf, 40 per cent, induces nearly normal growth to 
the adult size in the rat and induces a fair amount 
of reproduction and rearing of young. However, 
the animals fall considerably below the maximum 
performance in both these respects. 

An examination of other leaves of plants showed 
that the latter can in a general way be classed to- 
gether as food-stuffs of similar character, since they 
resemble each other more or less closely, just as the 



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DIETARY PROPERTIES OF VEGETABLES 43 

peeds all resemble each other in their dietary prop- 
,erties. The leaf proves to be a very different thing 
from the seed from the dietary standpoiat. The dry 
leaf usually contains from three to five times as 
much total ash constituents as does the seed, and 
is always especially rich in just those elements in 
^which the seed is poorest, viz., calcium, sodium and 
^chloriae. It follows, therefore, that the leaf supple- 
ments the inorganic deficiencies of the seed. The 
leaf, ia most cases, contains much more of the dietary 
essential, fat-soluble A, than is found in any seed, 
so that combinations of leaf and seed prove more 
satisfactory for the nutrition of an animal than do 
mixtures of seeds alone. The leaf contains protein 
and anaino-acids which result from digestion of pro- 
teins as does the seed. The amount varies from 8 
per cent of protein (nitrogen X 6.25) in such fleshy 
leaves as the cabbage, after diying, to more than 
15 per cent in the dry alfalfa or clover leaf. The 
seeds vary in their content of protein from about 10 
to 25 per cent. The leaf proteins appear, from 
the data available, to supplement and enhance in 
some degree the value of the seed proteins with which 
they are combined. The leaf supplements, therefore, 
all the nutritive deficiencies of the seed, but not 
necessarily in a highly satisfactory manner. 

It is interesting to reflect upon the reasons why 
the leaf of the plant should show such decided dif- 
ferences in its nutritive properties as contrasted 
with the seed. A consideration of the difference in 



44 THE NEWER KNOWLEDGE OF NUTRITION 

function of the two gives th,e clue to the cause. The 
seed consists of a germ, which fonns in most cases 
but a very small part of the entire seed, together 
with a relatively large endosperm. The germ con- 
sists of Uving cells, which respire and are capable of 
multipHcation (germination) when the conditions 
are favorable. In the wheat kernel the germ con- 
stitutes about 5 per cent of the entire seed. The 
endosperm, on the other hand, consists largely of 
reserve food materials such as protein, starch, 
sugars, fats and mineral salts. It is not living matter, 
and contains few cellular elements. The endosperm 
is, therefore, in most respects comparable to a mix- 
ture of purified food-stuffs. There is, as experiments 
have abundantly demonstrated, relatively Uttle of 
the dietary factor, wateivsoluble B, in the endosperm, 
and relatively much in the germ or embryo. The 
same is true for the second unidentified dietary 
factor fat-soluble A. This is practically absent from 
the endosperm, but is fairly abundant in the germ. 
Since the latter represents so small a portion of the 
entire seed, the seed itself is too poor in this sub- 
stance, in nearly all cases, to supply the needs of a 
growing animal. 

The leaf of the plant, on the other hand, is very 
rich in cells, and in most cases contains but Httle re- 
serve food material. It is the laboratory of the plant. 
Chlorophyll, its green pigment, enables it to make 
use of the energy of the simUght, and from the 
carbonic acid gas which it absorbs from the air, 



DIETARY PROPERTIES OF VEGETABLES 45 

together with water and mineral salts, which it 
absorbs from the soil through its roots, it builds 
up proteins, starch, sugars and fats, which are used 
for the growth of new plant tissue, or for storage ia 
the seed, tuber or other storage organs. The sur- 
faces of the leaf are a mosaic of living cells. They 
contain all the chemical complexes which are nec- 
essary for the nutrition of the animal cells, and are 
qualitatively complete foods. 

The quaUty of the leaf from the dietary standpoint 
may vary to a considerable extent. Some leaves are 
thin cellular structures, which dry easily in the sun 
when separated from the plant. In others, as the 
cabbage, the leaf is in some degree modified as a 
storage organ, and contains a considerable amount 
of sugars. The cabbage leaf likewise contains more 
than the ordinaiy amount of cellulose, which is its 
skeletal tissue. Its dietary properties are modified 
by these peculiarities in that the cellular elements 
are diluted by the more inert tissues and reserve 
food substances in the leaf. The freer a leaf is from 
the fimctidn of a storage tissue, the more intensified 
will be its leaf properties as a food. The fleshy leaves 
tend to have in some degree the dietary properties 
of the seed, and stand intermediate between the 
leaves, which are thin, and djy easily, and the seed 
in this respect. 

The Tubers. — ^After the seeds, the tubers of cer- 
tain plants constitute one of the most important 
classes of energy-yielding foods. The potato and 



46 THE NEWER KNOWLEDGE OF NUTRITION 

sweet potato are by far the most important rep- 
resentatives of this group ia Europe and the Amer- 
icas, but several other kinds of tubers are widely 
used as human food in the Orient. An examination 
of the potato has been recently made, which reveals 
the special dietary properties of this tuber to be just 
what we should expect from its function as a storage 
organ for reserve food in the plant. The functions 
of the potato are twofold, viz., to reproduce the 
plant in the following generation, and to furnish 
a food supply for the young potato plantlet while 
it is developing root and leaf systems which make 
it independent of the food stored ia the old tuber. 
The "eyes" of the potato represent groups of cells 
which are analogous to the germ of the seed. These 
are the points at which the potato sprouts when the 
conditions are appropriate. There is underneath 
the skin of the potato a layer of cells which are alive 
and respiring during the Mfe of the tuber, but the 
interior of the potato consists almost entirely of 
water, starch, protein, and to some extent of mineral 
salts. The cellular structures in the interior are 
gorged with starch, etc., and this portion is therefore 
analogous in its dietary properties with the endo- 
sperm of the seed. Both are comparable to a mixture 
of piuified protein, carbohydrate, and salts, which, 
as we have previously seen, is not capable of support- 
ing life. This portion, like the portion of the rice 
kernel, which remains after polishing, is almost 
lacking in both the chemically unidentified dietary 



DIETARY PROPERTIES OF VEGETABLES 47 

essentials, fat-soluble A and water-soluble B, and 
accordingly cannot support life even though it may- 
have an appropriate chemical composition as shown 
by analysis. The potato is to be classed with the 
seeds in its dietary properties, because it consists 
largely of reserve food materials and relatively httle 
of cellular elements. The results available indicate 
that if the potato is steamed and the thin paperlike 
skin removed without the loss of the cellular layer 
which lies just imdemeath, it wiU contain relatively 
more of the fat-soluble A, a lack of which leads to 
the development of the peculiar eye conditions pre- 
viously described, than do the cereal grains. Al- 
though it has not been subjected to experimental 
test, it would seem that a potato which is pared ia 
the ordinary way and the paring discarded, is 
changed in its dietary properties in much the same 
way as is the rice kernel during the polishing process. 
In the latter, the germ and the bran layer are both 
rubbed off, leaving the endosperm without the. small 
quota of cellular elements which it possessed in its 
natural state, and is correspondingly changed in its 
food value (see legend to Chart 3). The protein of 
the potato is not quite so valuable for growth as that 
of the cereal grains when fed as the sole source of 
this dietary factor.' 

There have been a number of experiments of short 
duration which gave results which indicate that in 
the human subject the nitrogen of the potato is of 
extraordinary value for replacing that lost through 



48 THE NEWER KNOWLEDGE OF NUTRITION 

daily metabolism in the adult. McCoUum, Sim- 
monds and Parsons, have tested this question by 
comparing with the protein of the cereal grains the 
value of the nitrogen, of the potato when this tuber 
was supplemented in such a manner as to make 
good all of its deficiencies except protein. The 
experiments involved growth tests in the young rat. 
The results show conclusively that potato nitrogen 
falls considerably below the value for growth pos- 
sessed by the individual cereal grains, when each of 
these serves as the sole supply of the digestion prod- 
ucts of protein. 

The Roots Employed as Food. — The same rea- 
soning applies to the root crops as to the potato, 
with respect to the relation- between dietary prop- 
erties and biological function. The roots which we 
employ as food are those which are highly modified 
as storage organs, and resemble the potato in con- 
taining a veiy high water and starch content, and 
but very little protein. Like the potato, there is a cel- 
lular layer at the periphery, and the interior is loaded 
with reserve food-stuffs. Appropriate feeding tests 
have shown that the properties of the beet resemble 
those of the seed and the tuber, rather than those of 
the leaf.' The fleshy roots and the potato and the 
sweet potato have an inorganic content which re- 
sembles that of the seed in a general way, so that an 
inspection of the analytical data relating to the 
composition of the ash of the seeds, tubers and roots, 
gave no promise that the combination in diets of 



DIETARY PROPERTIES OF VEGETABLES 49 

seeds with either of the latter classes of food-stuffs 
would correct the inorganic deficiencies of the former. 
Feeding experiments in which a seed and a tuber 
were combined, and so supplemented with purified 
protein, and fat-soluble A (in butter-fat), that all. 
the deficiencies of the mixture, except the inorganic, 
were made good, have shown that in the combinations 
of each of the more important seeds with the potato, 
the resulting mineral supply, which is derived solely 
from the natural foods themselves, is not of a char- 
acter suitable for the support of growth.' The con- 
tent of the elements, calcium, sodium and chlorine 
must be augumented by greater amounts before such 
food mixtures are complete with respect to their 
mineral content. No studies have as yet been made 
to determine the biological value of the nitrogen of 
the tubers other than the potato, and none at all of 
the edible roots. 

From the results of systematic feeding trials with 
mixtures of seeds alone and the same with single and 
multiple purified food additions, and the same type 
of experiment using certain of the tubers and root 
foods in place of the seeds, it is shown that all these 
classes of foodstuffs resemble one another in all re- 
spects except in the high content of water in the 
tubers and roots. In the dry state they are all much 
like the seeds, but there is one minor difference which 
should be mentioned. The most important difference 
Ues in the character of the nitrogenous compounds. 
In the seeds the nitrogen is almost all contained in 



50 THE NEWER KNOWLEDGE OF NUTRITION 

the form of true protein. In the tubers and edible 
roots most of it is in the form of much simpler com- 
pounds, a part being the same amino-acids which are 
derived from proteins on digestion. 

It is possible to prepare diets derived solely from 
vegetable products which will nourish an animal 
during growth and throughout life in a very satis- 
factory manner, but it is a surprisingly difficult task 
to prepare for the omnivera, an adequate diet com- 
posed entirely of food-stuffs of plant origin. While 
many of the seeds contain nothing of a detrimental 
character, many of the leaves, when eaten, undoubt- 
edly do introduce into the body substances which 
have more or less injurious effects. The nature of 
these cannot be stated at the present time, but the 
possibility that there may be an injurious effect 
brought about by prolonged administration of such 
bodies as the tannins, the glucosides and oxaJic acid, 
certain organic bases which in some cases resemble 
certain of the alkaloids, and in some leaves the pres- 
ence of alkaloids which are highly active pharmaco- 
logically, can easily account for the fact that with 
aU rations of strictly vegetable origin one would 
not have optimum nutrition. McCoUum and Sim- 
mon ds have in a long Ust of trials with mixtures of 
leaves and seeds been unable to secure the opti- 
mum of well-being in omnivorous animals. It is 
worthy of the greatest emphasis that in our hundreds of 
trials with diets derived entirely from vegetable sources, 
we have not succeeded in froducing optimum results in 



DIETARY PROPERTIES OF VEGETABLES 51 

the nutrition of an omnivorous animal the rat. Certain 
of the animals which we have restricted to foods of 
plant origm, have done so well that we should in the 
absence of much experience with diets of excellent 
quality, have considered them to be normal in every 
respect. It should be emphasized that the average 
performance of a group of people or animals living 
upon a varied diet cannot safely be assumed to repre- 
sent the best of which they are capable. In the 
study of diets the author and his colleagues have 
kept constantly in mind the best results we have ever 
seen in the nutrition of animals, as exemplified in 
rapidity of growth, ultimate size attained, number of 
young produced, and the success with which these 
Were reared, and have attempted to assign to every 
experimental group its legitimate place on a scale of 
performance, which has complete failvire to either 
grow or long remain aUve as the one extreme, and 
the optimum of which the animal is capable as the 
other. 

In connection with the statement which has just 
been made regarding the strict vegetarian diet, that 
it does not, so far as has been observed, induce the 
best results in the nutrition of the omnivora, it should 
be added that in human dietary practice what is 
generally designated as vegetarianism is in reality 
something very different. Many people bold that 
they are adhering to vegetarian dietary habits, who 
in reality, take 'm. addition to foods of plant origin, 
TT^ilk or eggs or both. This tj^pe of diet wiU give very 



52 THE NEWER KNOWLEDGE OF NUTRITION 

much better results than can be secured from the 
use of vegetable foods alone. Lacto-vegetarianism 
should not be confuesd with strict vegetarianism. 
The former is, when the diet is properly planned, 
the most highly satisfactory plan which can be 
adopted in the nutrition of man. The. latter, if 
strictly adhered to, is fraught with grave danger 
unless the diet is planned by one who has extensive 
and exact knowledge of the special properties of the 
various food-stuffs employed. 



•'i 



CHAPTER III 

THE VEGETARIAN DIET 

It has been pointed out in the. preceding chapters 
that it is not possible to make a diet derived entirely, 
from seeds or seed products, which will adequately 
nourish an animal during growth, and it may be 
added that such diets will not even maintain a fully 
grown animal in a state of health and normal physi- 
ological activity over a long period. Without an 
appropriate supplementing of seed mixtures with 
the elements, calcium, sodium and chloriae, no ap- 
preciable amount of growth has been secured with 
seed mixtures, in our extensive experience. It was 
further pointed out that the leaf is a very different 
thing from the seed, tuber or root, from the dietary 
standpoint, and these differences in nutritive prop- 
erties can be correlated with differences in fvinction. 
The seed is a storage organ of the plant, and is filled 
with a reserve supply of proteins, carbohydrates, fats 
and mineral salts. It is in great measure non-Uving 
matter, and indeed much of the contents of the seed 
was never a part of living matter, but only the prod- 
uct of it. In the leaf of the plant we have a tissue 
which, during life, was very active in the manifesta- 
►» tions of the properties of living matter. With these 

53 



54 THE NEWER KNOWLEDGE OF NUTRITION 

differences in function, it was pointed out, there are 
found corresponding differences ia the dietary values 
of the two types of foods, the latter being much more 
nearly complete foods chemically, than are the seeds, 
tubers and roots. 

Let us consider briefly the bearing of these obser- 
»vations on the whole subject of human and animal 
nutrition. It has-been pointed out that for majay 
years the protein and energy value and its digest- 
ibihty were assumed to determine the value of a 
food. The chemist is able to determine approxi- 
mately the amount of protein or rather its content 
of nitrogen which is taken as a measure of the amount 
of protein and the fuel value of a food, and by means 
of experiments on animals, the extent to which a 
given food is digested and absorbed. He can even 
tell by a study of the relation between the amounts 
of oxygen absorbed by the tissues, and the amount 
of carbon dioxide given off whether the animal is 
burning sugar or fat in order to obtain its energy. 
The nitrogen eliminated in the urine serves as a meas- 
ure of the destruction of protein in the body. With- 
out in the least attempting disparagement of the 
value of the services of the chemist in the study of 
the problems of nutrition, it may truthfully be ;,, 
said that both his ordinary and his unusual and 
most searching methods for the analysis of food- ' 
stuffs fail to throw any great amount of Hght on 
the value of a food or naixture of foods for induc- 
ing growth. • 



THE VEGETARIAN DIET 55 

In addition to the cereal grains, wheat, oat, maize, 
rye, barley and rice, the products of the vegetable 
garden which suppUed leafy vegetables, cabbage, 
lettuce, spinach, cauliflower, brussels sprouts, chard, 
celery, various "greens," etc.; roots, such as the 
radish, turnip and beet; tubers, such as the potato 
and sweet potato, we have had available as food an 
abundance of meats and of daiiy products. It is 
not strange that with such a supply of foods it should 
have been taken for granted that any diet consisting 
of wholesome foods, combined in such proportions 
and taken in such quantities as would fimiish 
the amounts of protein and energy which exper- 
iments on man and animals had shown to be neces- 
sary under specified conditions of hving, whether at 
rest or at work, should prove satisfactory for the 
maintenance of health in the adult and of normal 
growth in the young. An appreciation of the funda- 
mental importance of employing proper combinations 
of foods, was impossible, until the systematic efforts 
described in the first two chapters, were made to 
simplify the diet as far as possible, and to derive it 
from restricted sources. These studies have, when 
the results were applied to the interpretation of the 
quality of the diets of man in several parts of the 
world, revealed the fact that man is frequently 
faUing to make the wisest selection of food. Health 
and efl&ciency can be greatly improved by applying 
the knowledge which we now possess concerning 
the special properties of several classes of foods, to 



56 THE NEWER KNOWLEDGE OF NUTRITION 

the selection of the articles which shall make up the 
daily diet. 

The biological method for the analysis of single 
food-stuffs and mixtures of food-stuffs has made it 
evident that the older practice of regarding protein, 
energy and digestibility as the criteria of the value of 
a food mixture, must be replaced by a new method of 
presentation of the subject based upon a biological 
classification of the food-stuffs, the latter having its 
foundaiion in the function of the substance employed 
in the diet. Such a method of presentation of the 
subject of food values offers convincing evidence of 
the necessity, for the proper selection of food, that 
dietary reforms are greatly needed in many parts of 
the world. 

There has been much discussion of the relative 
merits of the vegetarian diet for man as compared 
with diets largely derived from vegetable foods but 
more or less hberally supplemented with foods of 
animal origin. This question has been discussed 
principally from the point of view of the supposed 
detrimental effects of a diet containing a high protein 
content, and the supposed beneficial effects of a 
sparing consumption of protein, and from the point 
of view that there are sound ethical reasons wHy 
man should abstain from the use of animal foods. 
The adherents of the latter extreme view have never 
become numerous, partly because the average ia- 
, dividual has not the self-control to enable him to 
forego the use of meats, milk and eggs, on account 



THE VEGETARIAN DIET 57 

of their appetizing qualities, and partly because the 
chances of one's succeeding in the selection of a 
strictly vegetarian diet which would maintain such 
a state of physiological well-being as would make 
possible the continuation of his line are very smaU. 
Concerning the ethical considerations involved in 
the eating of animal foods, nothing need be said here. 
The relative merits of the vegetarian as compared 
with the mixed diet, and the evidence regarding the 
desirabiUty of taking a low or high proteia intake, 
may next receive our attention. 

The most elaborate attempt to test the relative 
merits of the strictly vegetarian diet as contrasted 
with the omnivorous type, was made by Slonaker.^ 
He fed a group of young rats on a Ust of 23 vegetable 
foods, allowing them free choice within limits. For 
comparison, a similar group were fed the same foods 
of vegetable origin, but in addition animal food was 
given in moderate quantities. Since several natm-al 
foods, raw or prepared, were offered at a time, and 
the animals were allowed free choice as to what they 
should eat, and since no effort was made to keep 
track of the food consumption, or the relative 
amoimts of the different foods eaten, the results 
cannot be employed for critical examination except 
in a limited way. The results are of the greatest 
interest in showing how far instinct fails to guide 
an animal in the selection of its food. Slonaker's 
list of foods included nearly everything which a 
vegetarian in southern California would be likely 



58 THE NEWER KNOWLEDGE OF NUTRITION 

to have on his table during the year, and included 
seeds, the milling products of seeds and leafy veg- 
etables, tubers and roots. 

The vegetarian group grew fairly well for a time, 
but became stunted when they reached a weight of 
about 60 per cent of the normal adult size. They 
never increased in size beyond this poiat. The 
omnivorous controls grew steadily to what may be 
regarded as the normal size for the adult. The 
vegetarians lived, on an average for the entire group, 
555 days, whereas the omnivora had an average span 
of life of 1020 days. The vegetarian rats grew to be 
approxioiately half as large, and lived half as long 
as did- their fellows which received animal food. 
Slonaker drew the conclusion that a strictly veg- 
etarian diet is not suitable for the nourishment of an 
omnivorous animal, but was unable to say why this 
should be true. 

The results pf Slonaker were pubUshed in 1912, 
and just at the time when McCoUum and Davis were 
securing the experimental data which revealed the 
differences in the growth-promoting power of fats 
from different sources and which established the 
fact that a hitherto unsuspected dietary essential 
existed. They fed their diet of relatively pure food- 
stuffs described on page 16 with various fats of both 
animal and vegetable origin and found that no fat 
which was derived from plant tissues came in the 
growth-promoting class along with butter fat, the 
fats of egg yolk, and of the glandular organs. It 



THE VEGETARIAN DIET 59 

seemed to McCollum and Davis that the most 
probable explanation of the results of Slonaker was 
the absence or shortage in his vegetarian diet of the 
dietary essential which is furnished so abundantly 
by butter fat, and which later came to be designated 
as fat-soluble A and to a low protein iatake. With 
this idea in miad they tried during the s'ummer of 
1914 an experiment similar to that of Slonaker's, but 
modified so as to give the animals a much higher 
protein content than his rats probably took. It 
seemed that if Slonaker's vegetarian rats ate liberally 
of such leaves as cabbage and other leafy vegetables, 
the protein content of which in the fresh condition 
does not as a rule exceed 2 per cent, the content of 
other constituents of the diet m. proteia might not 
be high enough to give the entire mixture consumed, 
a proteia content sufficiently high to promote growth 
at the optimum rate. 

McCollxma and Davis, therefore, fed their rats a 
diet which afforded them a choice among the follow- 
ing hst of foods: wheat, maize, rye and oat kernels, 
cooked dry navy beans, peas, wheat germ, com 
gluten, wheat gluten, flax-seed oil meal, green clover, 
green alfalfa leaves, onions and peanuts. It will be 
observed that ia this list there are several vegetable 
foods having imusuaUy high protein contents. Com 
gluten, which is a product of the com starch manufac- 
ture, contains about 25 per cent of protein; wheat 
gluten, prepared by washing ground wheat free from 
starch, contains about 86 per cent; flax-seed oil meal, 



60 THE NEWER KNOWLEDGE OF NUTRITION 

as much as 30 per cent, and wheat germ about 30 pei 
cent of protein. Since animals are known to grow 
well on many diets containing 15 to 18 per cent 
of protein, it seemed that with these things to 
select from, one possible cause of failure in Slonaker's 
experiments, viz., too low a protein intake, would be 
ayoided. McCollum and Davis had not at that time 
discovered in the leaf the source of the dietary essen- 
tial, fat-soluble A, although it is now known that the 
leafy foods enable the herbivorous animal to thrive 
on his diet derived entirely from plant tissues. It was 
then assumed that when both the leaves and so 
many different seeds as well as the germ was supplied 
there could be little doubt that everything which a 
herbivorous animal requires was present in the foods 
supplied. 

The rats fed this wide variety of vegetable foods, 
and with a most liberal supply of protein, duplicated 
in all respects the results which Slonaker had de- 
scribed. They grew at about half the normal rate 
for the first few weeks, then became permanently 
stunted, none ever reaching a size much greater than 
half that of the average normal adult. The addition 
of butter fat to the diet of some of these animals 
failed to benefit them in any noticeable degree. The 
answer to the question as to why rats do not thrive 
on such strictly vegetarian food mixtures was not 
secured from these experiments. It was, however, 
soon after learned wherein lay the cause of failure of 
animals so fed. 



THE VEGETARIAN DIET 61 

McCoIlum, Simmonds and Pitz, began in 1915 a 
series of feeding experiments in which the diets of 
rats were derived solely from a naixture of one seed 
and one dry leaf.* In marked contrast to the failure 
of animals to grow on any mixtures of seeds it was 
found that in many cases a mixture of a seed with a 
leaf formed a diet on which considerable growth 
could be secured. Even poUshed rice, which as has 
been ah^ady described, requires four types of 
supplementing, viz, protein, mineral salts, fat- 
soluble A and water-soluble B, before it becomes 
dieteticaUy complete, was found to induce fairly 
good growth when fed with ground aHalfa leaves in 
the proportion of 60 per cent of the former to 40 per 
cent of the latter. On this simple monotonous ^lix- 
ture, young rats grew from weaning time to 83 per 
cent of the normal adult srze, and one female even 
produced two litters of yoimg, both of which were, 
however, allowed to die within a few days. A mix- 
ture of rolled oats, 60 per cent, and alfalfa leaves, 
40 per cent, groimd together makes a very much 
better diet. On this simple mixtm^ young rats have 
been observed to grow to the normal adult size, and 
to reproduce and rear young. One female reared 
fourteen out of seventeen young bom in three litters. 
Maize and alfalfa leaf, wheat and alfalfa leaf, are 
not so satisfactory for the production of growth as 
is ^ mixture of rolled oats and alfalfa leaves. Mix- 
tures of the latter leaf with legume seeds, peas and 
beans, give still poorer results. (Chart 6.) These 



62 THE NEWER KNOWLEDGE OF NUTRITION 

results made it evident that there is nothing in 
vegetarianisna per se, which makes it impossible to 
nourish an omnivorous animal in a satisfactory 
manner. It is only necessary to make a proper selec- 
tion of food-stuffs, and to combine them in the right 
proportions. In all the experiments described, in 
which the diet was made up of so simple a mixture 
as one leaf and one seed, they had not obtaiaed 
the optimum of growth, reproduction or rearing of 
young. 

It seemed probable that the reason why they did 
not more closely approximate the optimum in the 
nutrition of animals restricted to a cereal grain and 
a leaf, might lie in too low a protein mixtrure, or a 
protein mixture which was not of very high bio- 
logical value. In 1915, McCoUum, Simmonds and 
Pitz ' fed a group of young rats on a monotonous 
mixture consisting of maize 50 per cent, alfalfa 
leaf (dry) 30 per cent, and cooked (dried) peas, sub- 
sequently dried, 20 per cent. The three ingr-edients 
were ground together so finely that they could not 
be picked out and eaten separately. This diet La- 
duced growl h at approximately the normal rate and 
the production and rearing of a considerable number 
of young. The young grew up to the full adiilt size 
and were successful in the rearing of their offspring. 
Without ever tasting anything other than this mo- 
notonous food mixture, as their sole source of niJtri- 
ment after the weaning period, this family of rats 
remained nearly normal, and successfully weaned the 



THE VEGETARIAN DIET 63 

young of the fourth generation, with no apparent 
diminution ia. vitality. At this point the experiment 
was discontinued. 

The failure of Slonaker's rats to thrive on the 
vegetarian diet is to be explained on the basis of 
several faults. In the first place, the diet was of 
such a nature that the animals could hardly do othei^ 
wise than take a rather low protein intake. Sec- 
ondly, the leaves, which formed the only constituents 
of the food supply which contained enough mineral 
elements to support growth, were fed in the fresh 
condition. In this form the water content and buJk 
is so great that it would be practically impossible 
for an animal whose digestive apparatus is no more 
capacious than that of an omnivora, to eat a sufficient 
amount of leaf to correct the inorganic deficiencies 
of the rest of the mixture, which consisted of grains, 
seeds, tubers, and root foods. The same physical 
limitations would likewise deterjiiine that the animals 
would fail to secure enough of the fat-soluble A to 
supplement the deficiency of all the ingredients of 
their diet other than the leaves in respect to this 
.factor. This would not form so important a fault 
as the inorganic deficiencies, but would be an im- 
portant depressing factor. Thirdly, success or 
failure would turn in great measure on the extent 
to which the animals would be guided by instinct in 
the selection of the proportions of the several types 
of food-stuffs which was offered them. In the opin- 
ion of the author the appetite is by no means so 



64 THE NEWER KNOWLEDGE OF NUTRITION 

safe a guide for the proper selection of foods as has 
generally been supposed. 

From the results of the experiments just de- 
scribed it was necessary to conclude that the leaf 
differs from the seed in that it contains in satis- 
factory amounts the dietary factors which are found 
in the seeds in too small amounts. These include the 
three inorganic elements, calcium, sodimn and chlo- 
rine, the fat-soluble A and a protein supply which 
supplements at least in some degree the proteins of 
the seed. These, it will be remembered, are the 
three and only purified food factors which need be 
added to each of the seeds singly in order to make it 
dietetically complete. It is therefore, possible to de- 
vise a diet which is derived entirely from vegetable 
materials which will produce normal growth and 
the optimum physiological well-beitig. 

At the Iowa Experiment Station, Ewaid * has con- 
ducted extensive experiments of a character which 
were intended to demonstrate that the appetite and 
instincts of the hog serve to enable it to make such 
an adjustment of the relative amounts of the several 
food-stuffs offered it, as may induce better results , 
in the rate of growth than can be generally secured 
when the adjustment is made by the feeder, and 
the mixture of the ingredients of the ration are offered 
in a form which admitted of no choice by the animal. 
The data secured in many trials seem to show that 
there is some basis for the behef that this element of 
selection by the animal itself is worth taking ad- 



THE VEGETARIAN DIET 65 

vantage of. It should be mentioned that, as a rule, 
in all these trials the animals were given a choice of 
only three foods, one of these being a cereal grain, 
another, a protein-rich food and a third a plant leaf. 
In some experiments a salt mixture was made avail- 
able. The reasons for the employment of the leaf 
as a never failing constituent of the food supply of 
the growing pig could not have been explained be- 
fore the studies of McCoUum and his co-workers, 
with simplified diets and with diets restricted as to 
source to a single food-stuff, and until the latter had 
been fed with single and multiple food additions to 
ascertain the exact nature of the dietary faults of 
each. In connection with the types of diets em- 
ployed by Eward it should be mentioned that in 
case the animal ate fairly liberally of all the food- 
stuffs offered him, a serious mistake would be 
hardly made, since the proportions of the several con- 
stituents eaten couldbe varied to a considerable de- 
gree and growth stiU take place. In the case of the 
mixture of maize 50 per cent, alfalfa leaves 30 and 
peas 20, described above (Chart 7) it has been found 
that for the rat these are the best proportions in 
which these three ingredients can be mixed for the 
promotion of growth and reproduction. It has been 
fmiiher established that using these three food-stuffs, 
a moderate amount of growth may be seciu-ed, but 
few, if any, young wiU ever be produced if the mix- 
ture fed contains more than 50 per cent or less than 
20 per cent of alfalfa leaf. The importance of com- 



66 THE NEWER KNOWLEDGE OF NUTRITION 

bining the natural foods in the right proportions is 
easily seen from these results. It is interesting to 
note further, that shifting the proportions of maize, 
peas and leaf in this mixture over a range of 20 per 
cent does not materially change the protein content, 
or indeed, the chemical composition of the fbod mix- 
ture in any way, to a degree that could be expected to 
make so great a difference in the state of nutrition 
of the animals as is actually observed. 

There are now available the results of a very ex- 
tensive series of feeding trials in which the rations 
were made up of one seed, one leaf and one legume 
(pea, bean) in various proportions. These have 
failed to reveal any mixture which is quite the equal 
of the first ration of this type ever employed, viz., 
that composed of maize 50, alfalfa leaf 30 and peas 20 
per cent. It is, of course, easily possible that better 
mixtures of vegetable foods may be found by further 
search, but these results show: very definitely that 
for the omnivorous type of animal, whose digestive 
tract is so constituted that the consumption of large 
volumes of leafy foods is not possible, it is by no 
means a simple matter, if indeed possible, to derive 
the diet entirely from the vegetable foods, and se- 
cure the optimum of well-being. The data afforded 
by the experiments described form a demonstration 
of the fact that wide variety is of little value as la 
safeguard to nutrition. Chemical analysis, no matter 
how thorough, fails to throw much hght upon the 
dietary value of a food-stuff. The only way in which 



THE VEGETARIAN DIET 67 

the problems of nutrition can be solved is through 
numerous properly planned feediug experiments, 
but such studies were not possible before the solution 
of the problem of successfully feeding mixtures of 
purified food-stuffs. These studies led to the formula- 
tion of an adequate workiag hypothesis regarding 
what factors operate to make an adequate diet, and 
made possible the intetpretation of the cause of 
success or of failure with diets of the complexity em- 
ployed in daily life. It will be shown later that the 
consumption of milk and its products forms the great- 
est factor for the protection of mankind, in correcting 
the faults in his otherwise vegetarian and meat diet. 
The fact, that although the cereal grains each con- 
tain eveiy Inorganic element which is contained in 
an animal body, and every one which is a necessary 
constituent of the diet, but in too small amounts 
in the case of three of them, to enable the anUnals to* 
grow, revealed the ^neral constituents of the diet 
in a new and important Ught. The animal is sensi- 
tive to either the actual amounts of certain of the 
mineral elements in the food mixture, or to the re- 
lationships among them. Sidney Ringer was led 
in 1891 to his description of Ringer's solution, as the 
result of the observations ia physiology, that muscle 
behaves more nearly normally in solutions con- 
taining certain salts in definite proportions. Ringer's 
solution contains, for each 100 molecules of sodium 
chloride, two molecules of calcium chloride and two 
to one molecules of potassium chloride, together with 



68 THE NEWER KNOWLEDGE OF NUTRITION 

a trace of a magnesium salt. Loeb/ Howell * and 
others had described many experiments showing the 
profound effects upon the subsequent development 
of the eggs of varying in certain ways the composition 
of the salt solutions in which unfertilized eggs of 
certain marine animals were kept. In this way the 
earliest stages of development which are ordinarily 
observed only in the fertiUzed egg, could be caused 
to take place in eggs into which no sperm had en- 
tered. In the nutrition of the higher animals, it had 
never been made clear how dependent the organism 
is on the rate at which the blood stream receives 
mineral nutrient. The fact that the cereal grains 
are too low in three inorganic elements to admit of 
growth, made it clear that food packages just as they 
come from the hand of Nature, are not necessarily 
so constituted as to promote health. 



CHAPTER IV 

THE FOODS OP ANIMAL ORIGIN 

It is well known from common observation that 
milk, when it serves as the sole food of the infant, 
serves to keep it growing normally and in good 
health over a long period. There has occasionally 
arisen a discussion as to whether milk is a suitable 
food for the adult, and as to whether it is the "ideal " 
food. MDk, like the cereal grains and most other 
natural foods, contains all the essential food elements, 
and human experience teaches us that the proportions 
in which they occur in this product are much more 
satisfactbry than in many other natural foods. An- 
imals grow well on milk, but it is not easy to find 
even complex food mixtures of vegetable foods which 
wiU support optimum nutrition in the oinnivora 
during growth. 

Milk is deficient in iron, as is shown by chemical 
analysis. It has long been known that there is de- 
posited in the spleen of the new-bom animal a reserve 
supply of iron, which ordinarily suffices to tide it 
over the suckling period. Ordinary drinking water 
almost always contains small amoimts of iron, and 
this doubtless aids in some degree in preventing iron 
starvation in the infant. 

69 



70 THE NEWER KNOWLEDGE OF NUTRITION 

That milk is a complete food, capable of supplying 
all the nutrients necessary for the prolonged main- 
tenance of growth, health and the ability to produce 
and rear young, was shown by an experiment con- 
ducted by the author at the Wisconsin Experiment 
Station, A female pig was removed from its mother, 
which was stiU nursing it at the weight of 17 pounds. 
She had doubtless eaten of the mother's ration to 
some extent but her principle food had been her 
mother's milk. After removal from the mother, 
this pig was confined in a pen having a board floor, 
and was fed nothing but milk during a period of 17 
months. During the first few months only whole 
milk was fed, but later it was necessary to replace 
this in part by skim milk. The animal weighed 406 
pounds at the age of thirteen months. At this age 
she produced eight Uving and two dead pigs, and 
successfully brought the young to an average weight 
of seventeen pounds. She had access to wood shav- 
ings, and ate some of them. There can be no doubt 
that the milk which she consumed was enriched to 
some extent with iron by being in contact with cans 
having part of the surface free from tin. City drink- y 
ing water was also furnished and this contained/ 
appreciable amounts of iron. The animal must have 
been able to conserve its limited iron supply in a 
yety efficient manner. 

Milk is, therefore, capable of nourishing the pig 
during many months, with no other modification 
or additions than small amounts of iron. That it is 



THE FOODS OF ANIMAL ORIGIN 71 

best to select milk as a monotonous and restricted 
diet during adult life, no one familiar with the prin- 
ciples of nutrition would maintain. Milk is, however, 
without doubt our most important food-stuff. This 
is true, because the composition of milk is mjuih that 
when used in combination with other food^stuffs of 
either animal or vegetable origin, it corrects their dietary 
deficiencies. Combinations of equal weights of milk 
and one of the cereal gi'ains give excellent results 
in the nutrition of animals during growth, and grain' 
mixtures supplemented with milk support well in 
adult life the function of reproduction and rearing 
of young. This is because of the excellent quahty 
of its proteias, the peculiar composition of its in- 
organic content and the remarkable content of the 
dietary essential, fat-soluble A, in the fats of milk. 
Milk, like nearly all of the other natural foods, con- 
tains a greiat abundance of the second dietary essen- 
tial of unknown chemical nature, wateivsoluble B. 

The extraordinary value of the proteins of milk 
has been abundantly demonstrated by experiment. 
McCoUum ^ conducted a series of experiments with 
growing pigs to determine the extent to which they 
could retain the protein of the food for the construc- 
tion of new body protein. The pig was selected be- 
cause it is necessary in such studies to work with 
an animal whose growth impulse is as great as pos- 
sible. Only with such species is it to be expected 
that the animal will utDize the proteins for growth 
to the maximum extent made possible by the chem- 



72 THE NEWER KNOWLEDGE OF NUTRITION 

ical character of the food protein. The human 
infant has but little growth impulse because its 
period of infancy is long and the adult size not great 
as compared with the size at birth. A comparison 
of the human infant with the rat and the young pig 
(swine) in their capacity to grow in early life is of 
interest. The human infant weighs not far from 
seven pounds at birth, and during the first year of 
life is ordinarily able to multiply its initial body 
' weight by three, for the average weight at one year 
is about twenty-jone pounds. We may feed it himian 
milk the entire time, or unmodified cows' milk during 
the greater part of the year, without in any important 
degree modifying its rate of growth. In the latter 
case, we should be supplying it with perhaps double 
the amount of protein that it would receive were it 
fed human milk, since the latter contains on an aver- 
age about 1.6 per cent and the former about 3.5 per 
cent of proteiij.. 

In marked contrast to the feeble capacity of the 
human infant to store new tissue and increase in 
size, stand the rat and the pig. The rat at birth 
weighs about 4.83 grams, and contains about 0.064 
grams of nitrogen. At 280 days 'of age the male 
should weigh about 280 grams, and if moderately 
fat will contain about 8.5 grams of nitrogen. The 
rat is able, therefore, in a period of 280 days to 
multiply its initial body weight by about 55, 
and its initial body nitrogen content (protein) by 
133. 



THE FOODS OF ANIMAL ORIGIN 73 

The newborn pig weighing two poimds will con- 
tain about 134 grams of dry matter and 11.9 grams 
of nitrogen. In 280 days it may, if properly fed, 
reach a weight of 300 pounds. It would then have 
a nitrogen content of not less than 2407 grams. 
These changes in size entail a multiplication of the 
initial body weight by 150 and of the initial body 
nitrogen content by 202. The farm pig is ap- 
parently the most rapidly growing species of land 
animals. 

Such considerations determined the selection of the 
pig as a subject for the test of the biological value 
of the proteias of the various natural food-stuffs. 
The plan involved keeping the animal for a period 
of several days on a diet free from protein, but con- 
taining sufficient starch to cover the energy require- 
ments. When the nitrogen elimination in the urine 
reached a constant low level which represented the 
irreducible minimum, resulting from the "wear and 
tear" of the tissues, the animal was fed a diet con- 
taining protein derived solely from a single grain, 
or other single food-stuff. A record was kept of the 
intake of the element nitrogen, and of the daily loss 
of this element through the excreta, and from these 
records the percentage retained for growth was ob- 
tained. Similar experiments were carried out using 
milk as the sole source of protein. The following 
table summarizes the results obtained. 



74 THE NEWER KNOWLEDGE OF NUTRITION 

Pee Cent of Ingested Protein Retained fob Geowth by 
THE Pig 

Per cent of ingested 
Source of protein protein retained 

Com 20.0 

Wheat 23.0 

Oats (rolled) 26.0 

Milk 63.0 

The figures in the table are averages of a consider- 
able number of results and represent the general 
trend of the data. The experimental periods varied 
from 30 to 60 days. There can be no doubt that the 
proteins of milk are far superior to those of any foods 
derived from vegetable sources. 

The problem of determining the relative values of 
the proteias of the different foods when fed singly, sup- 
plemented with purified food additions that their diet- 
ary deficiencies were made good, was approached in 
a dififerent way by McCollum and Simmonds.^ Rats 
were fed diets in which the protein was all furnished 
by a single natural food-stuff, but the plane of protein 
intake was varied from very low to higher intakes, in 
Older to determine what was the lowest per cent of 
protein in the food mixture which woiildjust sufl&ce 
to maintain an animal without loss of body weight. 
The rations consisted of the following substances: 

Seed Amount to give the protein intake desired 

Growth-promoting fat (butter-fat) 5.0 per cent 

Suitably constituted salt mixtures 3to5 per cent 

Agar-agar (to furnish indigestible matter) 2.0 per cent 

Dextrin To make 100 per cent. 



THE FOODS OF ANIMAL ORIGIN 75 

The results showed that there are indeed very great 
differences in the amounts of protein from different 
seeds, which are necessary to maintain an animal 
without loss of body weight. The results for the 
more important seeds used as human foods are 
sununarized in the following table. 

Table Showing the Lowest Plane of Peotbin Intake De- 

KIVED FROM A SiNGLB SeED WhICH JuST SUFFICES TO MAIN- 
TAIN AN AinMAL IN Body Weight, when the Factors 
Other than Protein are Properly Constituted 

Source of Protein Plane of Protein Necessary for Maintenance 

Milk 3.0 per cent of food mixture ' 

Oat (roUed) 4.5" " " " 

Millet seed 4.5 " " " " 

Maize 6.0 " " " " " 

Wheat 6.0 " " " " 

Polished rice 6.0" " " " 

Flaxseed 8.0 " " " " " 

Navy bean 12.0 " " " " 

Pea 12.0 " " " " 

These maintenance experiments were of three to six months' 
duration. 

The data obtained with the pig is seen to be in 
harmony in a general way with those obtained with 
the rat, and help to substantiate the view which is 
supported by aU the evidence available, viz: that 
from the chemical standpoint, the dietaiy require- 
ments of one species of animal are the same as those 
of another. That there are great differences in the 
physical characters of the diet which suffice for. 



76 THE NEWER KNOWLEDGE OF NUTRITION 

or are required by certain species as contrasted with 
others, is a matter of common observation. The 
ruminants actually require coarse herbage as a part 
of their food, in order that the alimentary tract may 
function properly, whereas such physical properties 
in the diet of the omnivora are wholly out of place 
beyond very limited amounts. 

In considering the value of milk as a constituent of 
the diet it should be borne in mind that with respect 
to the protein factor it may enhance the value of the 
proteins of the remainder of the food. It may supply 
in relative abundance those amino-acids which are 
present in such small amounts that they form the 
first, second, etc., Hnaiting factors in determining the 
value of the protein for growth or maintenance, as 
well as by the direct addition to the food mixture, of 
the intrinsically good proteins of the milk. 

When taken as the sole food supply by the adult, 
milk is very liable to produce constipation and be- 
cause of its high protein content, may lead to the ex- 
cessive development of putrefactive bacteria in the 
intestine. The cages of rats fed solely on milk de- 
velop an offensive odor. The addition of carbohy- 
drate, such as starch or certain of the sugars, tend 
to cause the disappearance of the obnoxious flora from 
the alimentary tract, and the development, instead, 
of types which do not produce injurious decomposi- 
tion products in their action on proteins. 

Meats. — The muscle tissue of an animal con- 
sists of highly speciahzed tissue whose chief function 



THE FOODS OF ANIMAL ORIGIN 77 

is to produce mechanical work through contraction. 
It is in addition a storage organ in which glycogen, 
a form of starch, and also fats are stored as reserve 
foods. It contains but little of cellular structures in 
the sense that the glandular organs, such as the 
hver, kidney, pancreas, etc, do. Chemical analysis 
shows the muscle to consist, aside from the reserve 
food-stuffs, principally of water, protein and salts. 
The glandular organs yield a high content of nucleic 
acid, while the muscle tissue yields but little in pro- 
portion to its weight. The inorganic content of the 
muscle tissue resembles that of the seed of the plant, 
rather than the leaf both in amoimt and in the rel- 
ative proportions among the elements. 

Corresponding with the specialized function, and 
the peculiarities in composition just mentioned, we 
find that its dietary properties are comparable 
with the seed rather than the leaf. In fact, muscle 
tissue differs markedly from the seed in only one 
respect, when considered as a food-stuff, viz., in the 
quality of its proteins. These are distinctly better 
than those of the seeds with which investigations 
have been conducted. The inorganic content must 
be supplemented by the same inorganic additions as 
the seed, and the muscle proves to be relatively poor 
in its content of the unidentified dietary essential 
fat-soluble A, as compared with such foods as milk, 
egg yolk and the leaves of plants. 

Since the inorganic part of muscle resembles that 
of the seed, except that the latter is poorer in iron 



78 THE NEWER KNOWLEDGE OF NUTRITION 

and it is low in. its content of fat-soluble A, it does 
not supplement the seeds in an appreciable degree 
other than with respect to the protein factor. It 
follows, therefore, that we should not expect to se- 
cure growth and normal nutrition with mixtures of 
seeds, and meat and experimental trials demonstrate 
that this is the case. Mixtures of meat (muscle) 
and seeds require to be supplemented with respect 
to sodium, calcium and chlorine, just as do seed mix- 
tures alone*. The fat-soluble A content of such 
mixtures, unless millet seed is one of the seeds pres- 
ent to the extent of 25 per cent, must be increased 
by suitable additions before the optimum nutrition 
can be attained, and the animals can successfully 
bear the strain of reproduction and lactation. Meats 
are, therefore, but partial supplementary foods when 
employed with the seeds or the products prepared 
from seeds, such as wheat flour, com meal, polished 
rice, etc. Such diets can be partially corrected by 
the liberal use of leafy vegetables, but better by the 
use of the latter along with milk. 

The pronoimced deficiencies of muscle tissue as a 
food-stuff, naturally suggests the question of the 
reason for the success of the nutrition of the strictly 
carnivorous animals. The explanation is found in 
the order in which such creatures select the parts of 
the carcasses of their prey. The larger camivorse, 
after striking down an animal, immediately open the 
large veins of the neck and suck blood as long as it 
flows. Their second choice of tissues is the Uver, and 



THE FOODS OF ANIMAL ORIGIN 79 

following this the other glandular organs. Muscle 
tissue is only eaten after these have been consumed. 
With such a selection the animal secures eveiything 
which it needs for its nutrition except a sufficient 
amoimt of calcium, and this is obtained through 
■gnawing off the softer parts of the extremities of the 
bones. The failure of many camivora to thrive when 
confined in zoos, it probably the result of their being 
fed too largely upon muscle tissue and bones. They 
should be supplied with an abundance of the gland- 
ular organs and with blood to make their diet com- 
plete. With rats McCollum, Simmonds and Parsons 
have observed fairly satisfactory growth on equal 
parts of muscle tissue (round steak) and dried 
blood, whereas either of these alone cannot iaduce 
growth.* 

The Glandular Organs. — The liver and kidney 
may serve as typical examples of the glandular or- 
gans which are Employed as foods. There are cer- 
tain organs of internal secretion, such as the thy- 
roid, and suprarenal glands which elaborate products 
which are highly active pharmacological agents, and 
the Uberal use of these glands as food would lead to 
disastrous consequences. The glands contain but lit- 
tle of the inorganic elements in which the seeds are 
deficient. Their proteins are probably of excellent 
quality, but have not yet been carefully investigated. 
The glands consist largely of actively functioning 
cells, having specialized functions, and accordingly 
they prove to contain a more liberal amount of both 



80 THE NEWER KNOWLEDGE OF NUTRITION 

the fat-soluble A and water-soluble B than does the 
muscle. In respect to the former of the unidentified 
dietary essentials the glandular organs surpass the 
seeds in value.* From this description it will be 
seen that the glandular organs approximate more 
closely complete foods than does the muscle, but 
it*- is likewise apparent that these tissues do not 
form efficient supplements for the seeds and their 
products. 

Eggs.— The egg contains all the chemical com- 
plexes necessary for the formation of the chick dur- 
ing incubation. The egg is therefore to be expected 
to furnish everything which is needed for the nutri- 
tion of a mammal, ;for as has been already stated, 
the evidence all supports the beUef that the chemical 
requirements of one species are the same as another. 
The egg is indeed a complete food, but not one which 
produces the optimum results when employed as 
the sole source of nutriment. Aside from the calcium 
content of the white and yolk of the egg, which is 
much lower than that of milk, the contents of the egg 
resemble milk in a general way in nutritional value. 
The high content of milk sugar in the latter, and the 
almost complete absence of carbohydrate from the 
egg, cause them to differ considerably in the physi- 
ological results which they produce on animals when 
each is fed as the sole source of nutriment. "Egg, 
when fed alone, encourages much more than milk 
the development of putrefactive organisms in the 
alimentary tract. The shell of the egg consists 



THE FOODS OF ANIMAL ORIGIN 81 

principally of calcium carbonate, and during in- 
cubation this is to some extent dissolved and ab- 
sorbed for the formation of the chick. When eggs 
serve as human food the shells are discarded. There 
are distinct differences in the chemibal natures of 
the constituents of eggs as contrasted with milk. 
The principal protein of egg yolk, like that of milk, 
contains phosphorus, but the fats of milk are phos- 
phorus free, whereas phosphorized fats (e. g., leci- 
thins) are very abundant in egg fats. There is an 
abundance of lactose in milk, whereas the egg con- 
tains but a trace of sugar. These differences have 
little, if any, dietary significance. The yolk is es- 
pecially rich in both the fat-soluble A and water- 
soluble B. With the exception of milk the foods of 
animal origin do not supplement completely the diet- 
ary deficiencies of the seeds and their products. 

We are now able to make certain generaUzations 
of fimdamental importance regarding the types of 
combiaations of the natural food-stuffs which may 
be expected to give good results ia the nutrition of 
an animal. 

(1) Seed mixtures, no matter how complex, or 
from what seeds they are derived, will never induce 
optimum nutrition. 

Seeds with tubers, or seeds with tubers, roots and 
meat (muscle) wiU in all cases fail to even approxi- 
mate the optimum in the nutrition of an animal 
during growth. 

(2) The only successful combinations of natural 



82 THE NEWER KNOWLEDGE OF NUTRITION 

foods or milled products for the nutrition of an ani- 
mal are: 

(a) Combinations of seeds, or other milled 
products, tubers and roots, either 
singly or coUeqtively taken with suf- 
ficient amounts of the leaves of plants. 

(b) Combinations of the food-stuffs enu- 
merated under (a) taken along with a 
sufficient amount of nulk to make good 
their deficiencies. 

Milk and the leaves of plant are to he regarded as 
protective foods and should never be omitted from the 
diet. Milk is a better protective food than are the leaves, 
when used in appropriate amounts. 

It should be appreciated that not all diets which 
conform to the requirements laid down in the above 
generalizations, will give equally good results. This 
is especially true of diets of the type under (2). 
Chart 6 shows the great differences in the food 
values of a few mixtures of seeds and leaves. It can 
be stated definitely, however, that diets which are 
not made up according to the second plan, will 
never be satisfactory. 



CHAPTER V 

THE DISEASES REFERABLE TO FATJI/TT DIET, OR THE 
SO-CALLED "deficiency DISEASES" 

It has been pointed out that in the year 1911 Funk 
took up the study of the disease beri-beri. He made 
use of the observation of Eijkman, that the symp- 
toms could be produced experimentally in birds by 
feeding them exclusively upon polished rice for two 
to four weeks, whereas birds remain for much longer 
periods ia a state of health when fed exclusively upon 
the unpohshed grain. He also made use of the ob- 
servation of Fraser and Stanton, that an alcohoKc 
extract of rice poUshings would effect a "cure" of 
polyaeuritic birds. Funk made numerous elaborate 
and painstaking attempts to separate the "curative"* 
substance, and wrote extensively on what he believed 
to be "deficiency" diseases. Under this term he 
included beri-beri, scurvy, pellagra and rickets. 
Hopkins discovered that small additions of milk 
to food mixtures composed of purified protein, 
carbohydrate, fats and inorganic salts, rendered them 
capable of inducing growth, whereas without such 
additions no growth could be secured. The effects 
were out of all proportion to the energy, or protein 
value of the added milk, and he suggested the exist- 

83 



84 THE NEWER KNOWLEDGE OF NUTRITION 

ence of "accessory" food-stuffs, which are required 
in but small amounts, and which are absent from the 
mixtiu-es of purified food-stuffs, which fail to promote 
growth. To the supposed "curative" substances, 
the presence of which in the diet prevents the develop- 
ment of several syndromes enumerated, Funk gave 
the collective name "vitamines." Thus he distin- 
guished an antineuritic "vitamine," an antiscorbutic 
"vitamine," etc. These supposed substances have 
since been variously designated as "growth sub- 
stances," "growth determinants," "food hormones," 
"accessory" food substances, etc. 

McCollum and Davis through their studies with 
diets of purified food-stuffs, pointed out that it was 
highly probable that .there are essential in the diet 
but two substances rather than groups of substances 
of unknown chemical nature, and it was shown, as 
has been pointed out, that one of them is associated 
with certain fats, while the other is never found with 
' the isolated fats of either animal or vegetable origin. 
MeCoUum and Kennedy * suggested that they be 
provisionally called fat-soluble A and water-soluble 
B, because of their characteristic solubility in fats 
and in water respectively. 

The above terms, except the last two, are mis- 
nomers. The word accessory, carries the idea that 
the substances in question are dispensable. Con- 
diments may be desirable, but they can be dispensed 
with and are properly designated as accessory food 
substances. An indispensable food complex cannot 



"DEFICIENCY" DISEASES 85 

properly be designated by this tenn. "Vitamine" 
is objectionable, because the prefix vita connotes an 
importance of these dietary essentials greater than 
other equally indispensable constituents of the diet, 
such as certain of the amino-acids which play a r61e 
in protein metabolism. The ending amine has a 
definite and specific meaning in organic chemistiy, 
beiag used to designate a compound derived from 
ammonia by the substitution of one or more of its 
hydrogen atoms by various organic radicals. Any 
substance to be properly designated as amine must 
contain the element nitrogen. There is no evidence 
that either of these unidentified dietary essentials 
is an amine, and indeed fat-soluble A probably con- 
tains no nitrogen, for it is especially abundant in 
butter fat, and the latter is practically free from this 
element. 

"Food hormones" is an objectionable term, be- 
cause aU the evidence available indicates that both 
the fat-soluble A and water-soluble B are never- 
failing constituents of the cells of both animal and 
plant tissues. They have nothing in common with 
the hormones. The latter are chemical substances 
which are formed in the body by special tissues and 
contributed to the blood stream where they cause 
the stimulation of certain other tissues to physiolog- 
ical activity. They are chemical messengers, while 
the substances under discussion are food complexes, 
apparently necessary for all the living cells of the 
body. It has been pointed out that the content of 



86 THE NEWER KNOWLEDGE OF NUTRITION 

both of these two dietary essentials appears to run 
parallel to the content of cellular elements in the 
food-stuffs, regardless of their source. 

"Growth substances" and "growth determinants" 
are not good terms for the reason that the substances 
in question are just as essential for the maintenance 
of a full grown animal in a state of health as they are 
for the support of growth in the young. Further- 
more, in actual experience, rations are found in 
which the content of one or more essential amino- 
acids are present in such amounts that they form 
the Umiting factor which determines the value of the 
ration. It is easy to prepare a food mixture in which 
any one of the eight or nine essential inorganic 
elements which the diet must furnish, wiU be so low 
as to prevent the growth of an animal even though 
the food is otherwise of satisfactory character. In 
one case the addition of a suitable sodium compound 
or in another a calcium or a potassimn salt might 
induce growth, and these elements might, with just 
as much propriety, be called "growth determinants" 
as to apply this term to one of the still unidentified 
food essentials. The term might fittingly be applied 
to any of the indispensable components of the diet, 
such as certain of the amino-acids, which result from 
the digestion of the proteins. 

All natural food-stuffs, such as the seeds of plants, 
the leafy vegetables, fruits, roots, tubers, meats, 
eggs and milk, contain certain amounts of all the 
substances which are indispensable components of 



^ 






1 


t 


A 


aracter 
1. The 
plants, 
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lund in 
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CD T3 OT O +e Q, 










in th( 
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leave 
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I 








-% ^ 2 ^ -o ^ 


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tly alike ex 
cent of sun- 
olk fats and 
nknown, wl 
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iet causes t 


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were exac 
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left was g 
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The on 
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chemica! 
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. 5.— The 1 
fat which 
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ar eye dise 








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O O o bC C3 a* 


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"DEFICIENCY" DISEASES 87 

the diet. There is, however, great variation in the 
quality of the different foods with respect to the sev- 
eral factors. Some contain much protein, others 
little, and a similar variation with respect to other 
constituents is found. The special properties of the 
several groups of food-stuffs have been described in 
Chapters III and IV. 

The best sources of fat-soluble A are whole milk, 
butter fat and egg yolk fats and the leaves of plants. 
The seeds of plants contain less and those products 
derived from the endosperm of the seed are very 
poor in this substance. Such food-stuffs as bolted 
flour, degermioated com meal, poUshed rice, starch, 
glucose and the sugars from milk, cane, and beet are 
practically free from the fat-soluble A. The specific 
result of a lack, of a sufficient amount of this sub- 
stance iu the diet is the development of a condition 
of the eyes which appears to be rightly classed as a 
type of xerophthalmia. The eyes become swoUen 
so badly that they are opened with difficulty or not 
at all. The cornea becomes inflamed, and unless 
the missing dietary essential is supplied, bUndness 
speedily results. Osborne and Mendel ^ have also 
noted this condition in experimental animals and 
its relief by feeding butter fat. The introduction 
into the diet of 5 or more per cent of butter fat 
will cause prompt recovery in cases where the an- 
imals are within a few days of death. Complete re- 
covery takes place within two weeks if the sight has 
not been destroyed. The normal condition of the 



88 THE NEWER KNOWLEDGE OF NUTRITION 

eyelids can be restored even after the sight is gone 
and the cornea has faded. 

When the diet consists principally of one of the 
cereal grains such as the wheat, oat or corn kernel, 
or even a mixture of these, and it is satisfactorily 
supplemented with respect to the inorganic elements 
in which they are deficient, viz., calcium, sodium 
and chlorine, and their proteins are enhanced in 
value by the addition of a proteiu of good quality, 
animals restricted to such a food supply may long 
escape the onset of this disease. The seeds are not 
entirely lacking in the substance, fat-soluble A. 
They contain, especially the wheat and com kernels, 
about half the amount required to maintain an 
animal iu a state of health. If the seeds or their 
mixtures are supplemented with respect to but a 
single dietary factor, e. g. inorganic salts, but the 
protein content is left of relatively low biological 
value, the debiUtating effects of the low value of the 
food mixture ia the two dietary factors (protein and 
fat-soluble A) simultaneously will hasten the onset 
of xerophthalmia.' When judging the effects of the 
diet on an animal, it is necessary to take into account 
the fact that the diet is a complex thing, and that if 
it is properly constituted with respect to all factors 
but one an animal may tolerate it without apparent 
injury whether the fault lies in one or another of the 
essential components. The value of one component 
may fall well below that which will lead to serious mal- 
nutrition, when a second dietary factor is likewise poor. 



m/r 




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diet, 
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Fig. 6. — From w 

of the fats which th 

•- while the one on th 

mal rate, while the 

in Figures 5 and 6 1 







"DEFICIENCY" DISEASES 89 

The idea should not be entertained that butter 
fat is ttie only food which supplies the fat-soluble A. 
If the diet contains a liberal amount of milk, eggs, 
glandular organs or the leaves of plants," it wiU, if 
otherwise satisfactorily; constituted, prevent the 
onset of the eye disease. The seeds and seed prod- 
ucts, such as wheat fiotir (bolted), degerminated 
com meal, polished rice, starch, the sugars, syrups, 
tubers, roots, such as the radish, beet, carrot, turnip, 
etc., and also the muscle tissue of animals, such as 
bam, steak, chops, etc., do not contain enough of 
the fat-soluble A to be classed as important sources 
of this dietary essential. The tubers and roots 
appear to be somewhat richer in it than are the 
seeds.* In the form ia which they are ordinarily 
eaten, as mashed or baked potato, baked sweet 
potato, fresh or creamed radish, cooked carrots, 
beets or creamed turnips, the water content of the 
dish as served is so high that the amount of solids 
eaten is not a very high pet cent of the total food 
supply, and the protective action is correspondingly 
limited. In America, however, potatoes are seldom 
eaten 'without the addition of butter. The vegetable 
fats and oils such as olive oil, cottonseed oil, peanut 
and cocoanut oils, although good energy yielding 
foods, do not furnish this dietary essential. The 
body fats of animals such as lard, beef fat, etc., are 
not important sources of the fat-soluble A. 

MeCoUtma and his co-workers have repeatedly 
observed in experimental animals the type of xeroph- 



90 THE NEWER KNOWLEDGE OF NUTRITION 

thalmia of dietary origin which has been described 
above. They have many times rescued animals 
from the threshold of death by the addition of 
butter fat to the diets of the animals which were 
suffering from the disease which was brought about 
by a lack of a sufficient amount of the fat-soluble A * 
in their food. It is important to inquire whether 
or not this disease has ever occurred in man. It is ' 
not easy to decide from the descriptions, in the clin- ss 
ical literature, of the eye troubles of poorly nourished ■ 
peoples in various parts of the world, which are of 
the peculiar type with which we are now dealing, 
and which are due to other causes. Soreness of the 
eyes is common among many primitive peoples. 
Herdlika ^ describes severe eye troubles among the | 
American Indians of the southwest, and attributed j 
them to too great exposure to strong sunlight. In- 
fection of the eyes is common among many peoples, 
and the clinician, not being aware of the existence 
of a pathological condition of the eyes due to faulty 
diet, would, of course, be inclined to attribute such 
conditions to other causes. 

There are several instances of the occurrence of . 
conditions described in the Uterature as xerophthal- 
mia, which seem to be beyond question, cases in 
which the disease has occurred in man as the result ;^ 
of specific starvation for the dietary essential, fat- ■•^, 
soluble A. Mori ^ in Japan described in 1904, four- 
teen himdred cases of xerophthalmia among children 
in a time of food shortage. He describes the condi- : 



"DEFICIENCY" DISEASES 91 

tion in a manner which agrees closely with that which 
MeCoUum and Simmon ds have observed in animals 
whose diets were lacking in a sufficient amount of 
fat-soluble A. The evidence that he was dealing 
with this disease is made almost conclusive by the 
fact that he states that feeding chicken livers effected 
a cure. It has been already mentioned that the 
glandular organs contain the fat-soluble A in fairly 
Uberal amounts. The Japanese have, as a rule, no 
dairy products. Their diet consists of seeds and 
seed products, roots, tubers, leaves and meats, prin- 
cipally fish. Their principal sources of the dietary 
factor in question are the leafy vegetable and eggs, the 
former of which in normal times they consume much 
larger amounts than do the peoples of most parts 
of Europe and America. Shortage of food will occur 
usually owing to drought, and the first products 
which fail are the green vegetables, and accordiagly 
the dietary essential which would be least abtindant 
wotdd be the fat-soluble A. Mori attributed the 
xerophthalmia to fat starvation. It seems highly 
probable, however, that a lack of fat was not ia it- 
self the cause of the disease, but rather the lack of 
the unidentified dietary essential which is associated 
with certain fats, but is not fmmished by any of the 
isolated fats of vegetable origia, although it is present 
in plant tissues where these contain cellular struc- 
tures. Mori states that the disease does not occur 
among fisher folk. 
Bloch '' has recently described forty cases of severe 



92 THE NEWER KNOWLEDGE OF NUTRITION 

necrosis of the cornea with ulceration, in the vicinity 
of Copenhagen. The children had been fed nearly 
fat-free separator skim milk, and were atrophic or 
dystrophic and anemic. He attributed the disorder 
to fat starvation, since the, children responded with 
recovery when fed breast milk, or in the case of older 
ones, with whole mUk mixtures and to codliver oU 
administration. The recovery, it will be noted, 
followed the feeding of those substances which are 
good sources of the fat-soluble A. 

Czerny and Keller ^ describe a similar condition of 
the eyes in children suffering from malnutritioii as 
the result of being restricted to a cereal diet. 

It seems certain that these cases of xerophthalmia 
should be looked upon as a "deficiency disease" 
not hitherto recognized in its proper relation to diet. 
It is not a fat starvation, but, if it be the same condi- 
tion which McCoUum and Simmonds have definitely 
shown to be readily relieved in its early stages by 
the administration of such foods as contain liberal 
amounts of fat-soluble A, it would not be relieved 
by feeding with vegetable fats in any amounts. Milk, 
eggs, leafy vegetables and the glandular organs, 
are the foods which serve to protect against a short- 
age of this indispensable dietary component. This 
type of xerophthalmia is analogous to beri-beri, ra 
that it is due to the lack of a specific substance in 
the diet. Beri-beri and xerophthalmia are according 
to McCoUum and Simmonds, the only diseases refera- 
ble to faulty diet, which are to be explained inthis way. 



"DEFICIENCY" DISEASES 93 

Beri-beri is a disease common in the Orient among 
peoples who limit their diet largely to pohshed rice 
and fish. It has, in recent years, been described in 
Laborador owing to excessive consmnption of bolted 
floiu-,' and in Brazil among laborers whose diets were 
of varied character, but not judiciously chosen.'" 
Its most striking characteristic is a general paralysis, 
and it is frequently referred to, especially when pro- 
.duced experimentally in animals, as polyneuritis. 

The disease was first produced in animals by 
Eijkman *' in 1897. He discovered that when 
pigeons and chickens were restricted to a diet of 
polished rice, they steadily lost weight and in time 
came to majiifest all the essential symptoms char- 
acteristic of beri-beri in man. In pigeons the disease 
usually appears in two or three weeks. He found 
that feeding rice polisMngs would produce a rehef 
of the symptoms. This result suggested that there 
was lacking from pohshed rice, something which was 
necessary for the maintenance of health in the bird, 
and that that something was present in the rice 
pohshingg. This was the first experimental evidence 
that there is necessary in the diet substances other 
than proteins, carbohydrates, fats and inorganic salts. 

The observations of "Eijkman attracted but Uttle 
attention imtU Funk '^ took up the study of beri- 
beri in 1910. Fraser and Stanton had, as early as 
1907, employed alcohoUc extracts of rice pohshings 
for the cure of experimental polyneuritis. Fxmk 
made numerous studies directed toward the isolation 



94 THE NEWER KNOWLEDGE OF NUTRITION 

and study of the substance which exerts the curative 
effect, and developed iu his writings the well-known 
"vitamine" hypothesis. This hypothesis postulated 
the existence of a similar protective substance for 
each of the diseases scurvy, pellagra and tickets, 
in addition to that which in the normal diets pro- 
tects against beri-beri. 

Funk had experimental evidence in support of his 
theory only in the case of beri-beri. The evidence . 
that the other diseases which he included in. the 
category of "deficiency" diseases are due to the lack 
of specific complexes, was of the nature of clinical 
observations, rather than well controlled experiments. 
The peculiar value of butter fat was unknown to 
him, and he classed it among the food substances 
which contain no "vitamine" because its administra- 
tion to polyneuritic pigeons produced no beneficial 
effects." Funk deserves great credit for the evidence 
which he secured that the amount of the substance 
which can be extracted from rice polishings, which is 
necessary to cause the relief of polyneuritis in a 
pigeon, is exceedingly small. A few milligrams of 
material which is still contaminated with impurities 
suffices to bring about relief in a bird which is in a 
helpless condition and within' a few hours of death, 
and to make it appear like a normal pigeon. The 
effects seem to be out of all proportion to the amount 
of substance administered. Fimk's studies were con- 
firmed and extended by ■ the important work of 
WUliams." 




|lfi||ii 



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oj M a 
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"DEFICIENCY" DISEASES 95 

There can be no doubt that there are two "de- 
ficiency" diseases in the sense in which Funk and 
his school employed this term. One of these is 
beri-beri and the other the type of xerophthalmia 
which McCollum and Simmonds have pointed out 
as occurring occasionally in man as the result of 
faulty diet, and have demonstrated to be the 
same condition which results in animals as the re- 
sult of specific starvation for the unidentified di- 
etary essential fat-soluble A. It is of the greatest 
importance to determine whether scurvy, pellagra 
and possibly rickets are likewise to be attributed to 
the lack of similar substances of a specific nature in 
the diet. It has already been mentioned in Chapter 
II that from a knowledge of the dietary properties 
of the oat kernel, McCoUum and Pitz concluded 
from a study of experimental scurvy in the guinea 
pig, that this disease, while referable to faulty diet, 
does not result from the absence of any special sub- 
stance from the diet. The evidence upon which this 
conclusion rests has been touched upon (page 36) 
and will be next briefly considered. 

The oat kernel, when submitted to the biological 
method of analysis described in the first chapter, was 
found to contain all the chemical elements and com- 
plexes necessary for the promotion of growth and 
health in a mammal, but not in suitable proportions. 
Like other seeds it requires certain inorganic addi- 
tions, and its content of the unidentified fat-soluble 
A is entirely too small to permit of growth, or to 



96 THE NEWER KNOWLEDGE OF NUTRITION 

protect an animal against the eye disease, xeroph- 
thabnia. In addition, its jjroteins are not com- 
parable in value with those of such foods as milk, 
eggs and meats. The important fact was demon- 
strated by McCollxma, Simmonds and Pitz, that 
if the extracts of natural foods which we have long em- 
ployed in our experimental work and which we desig- 
nate water-soluble B, contain any physiologically in- 
dispensable substance other than that which prevents 
beri-beri, the oat kernel contains all of these. This 
follows from the fact that they were able to induce 
normal growth and prolonged well-being in animals 
fed the oat kernel supplemented only with purified 
'food substances, — ^viz: protein and iaorganic salts, 
and a growth-promoting fat. The latter term 
is used to designate a fat containing the fat- 
soluble A. 

McCollum and Pitz observed that the guinea pig 
(Suffers from scurvy, not only when restricted to a 
diet of oats, as stated by Hoist, but likewise when fed 
oats and all the fresh milk it will consume. Jackson 
and Moore ^^ made this observation independently 
and described it several months previous, in their 
excellent studies of the bacteriology of the digestive 
tract and tissues of the guinea pig, after the animals 
have developed the disease as the result of an ex- 
clusive oat and milk diet. Milk alone is a complete 
food, and suffices for the maintenance of growth and 
a good state of nutitrion in several species of animals, 
such as the rat and swine. It cannot, therefore, be 



■ "DEFICIENCY" DISEASES 97 

lacking in any unidentified food substance. Why, 
then, should the guinea pig suffer scurvy when re- 
stricted to a diet of oats and milk? 

McCoUum and Pitz found in the guinea pigs which 
had died of scurvy, that the cecum which is a very 
large and very delicate pouch through which the 
food must pass in going from the small ta the large 
intestine, was always packed with putrefying feces. '^ 
They decided that the mechanical difficulty which 
the ammals have in the removal of feces of an un- 
favorable character from this part of the digestive 
tract was in some way related with the development 
of the disease. That this assumption was correct, 
was shown by the fact that the administration of 
liquid petrolatum, a "mineral" product to which no 
food value can possibly be attributed, served to re- 
lieve a certain number of animals after they were 
near death from the disease, whUe confined strictly 
to the diet of oats and milk which caused them to 
develop scurvy. The explanation which they offered 
was that the liquid petrolatum served to improve 
the physical properties of the contents of the packed 
cecum, and thus enable the animals to rid themselves 
of this mass which was undergoing putrefactive de- 
composition. 

Further experiments showed that when the ani- 
mals were fed an oat and milk diet, to which was 
added suitable doses of phenolphthalein, a ca- 
thartic, they could withstand the diet for long 
periods without developing scurvy. This, accord- 



98 THE NEWER KNOWLEDGE OF NUTRITION 

ing to McCoJlum and Pitz, was due to the addi- 
tional secretion of water into the digestive tract, 
brought about by the cathartic, and repulted in 
softening the feces so that they were more easily 
eliminated from the cecum. 

It has long been known that orange juice is a very 
efficient protective agent against scurvy, both in man 
and the guinea pig. In fact it was because of the 
spectacular relief of the disease by the administration 
of orange juice or of fresh vegetables, that Funk 
was led to the belief that scurvy is, like beri-beri, 
due to the lack of some specific chemical substance 
from the food supply. McCoUum and Pitz further 
tested their theory by preparing an artificial orange 
juice, in which every constituent was known, and 
the administration of this to guinea pigs which were 
confined to a diet of oats and milk, on which food 
supply they almost invariably develop the disease.' 
The "artificial orange juice "consisted only of cit- 
ric acid, cane sugar and inorganic salts, in about the 
proportions in which these occur in the edible portion 
of the orange. It was demonstrated that this mix- 
ture exerted a decidedly protective action when added 
to the oat and milk diet, and prevented the develop- 
ment of scurvy over a long period. 

Jackson and Moore suggested that scurvy is a 
bacterial disease, and they have secured experimental 
evidence which strongly supports that view. They 
found in the hemorrhagic joints a diploccocus, which 
may have a causal relationship to the disease. They 







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"DEFICIENCY" DISEASES 99 

were able to induce mild symptoms of scurvy by the 
iajection of bacterial cultm-es into animals which 
were fed upon a diet which regularly maintains the 
guinea pig in a state of health. McCollum and Pitz 
hold the view that there may be an invasion of the 
tissues by organisms as the result of injury to the 
cecal wall, when the animals are debiUfcated. The 
cecum is injured by long contact with the irritating 
products formed by putrefactive bacteria acting on 
the protein substances contained in the cecum when 
it becomes packed with feces of such a character 
that they cannot be eliminated. They suggested the 
alternative hypothesis that there may be formed 
through bacterial activity, substances which are 
toxic, and have such pharmacological properties as 
cause injury to the walls of the capillaries of those 
areas in which hemorrhage is observed in scin^'y. 
There are several problems still to be solved in con- 
nection with the cause of scurvy, but it seems to be 
satisfactorily demonstrated that it is not a "de- 
ficiency" disease in the sense in which are beri-beri 
and the type of xerophthalmia of dietary orgin. There 
is, according to McCollmn and bis co-workers, no 
protective substance against this disease. Diets of 
faulty character, and especially bacteriologically un- 
satisfactory, are responsible for its etiology, and it 
is relieved by a satisfactory diet. The peculiar ana- 
tomical structure of the alimentary tract of the 
guinea pig makes it difficiilt for it to thrive unless 
its diet contains a succulent vegetable, which gives 



100 THE NEWER KNOWLEDGE OF NUTRITION 

the feces favorable physical characters and which 
makes them easy of elimination. 

Hess " has recently described the results of his 
observations on infants which were fed milk treated 
io various ways, and these are of great significance 
in throwing Ught on the cause of scurvy. He points 
out that for a period of two years milk which had 
been pasteurized commercially at 165° for thirty 
minutes was employed in feeding the iafanfcs in his 
charge. For two subsequent years the dealers raised 
it' to only 145° for thirty minutes. In his experience 
the former milk was more likely to induce scurvy 
than the latter. Hess thereafter secured raw cer- 
tified milk and pasteurized it at the institution for 
thirty minutes at 145.° Infants fed this milk did not 
develop scurvy in any instance, and one which 
showed symptoms of subacute scurvy improved on 
the home pasteurized milk. How did this milk differ 
from the commercially pasteurized milk which did 
show definite tendency to induce the disease? He 
points out that it differed mainly in the interval 
which elapsed between the time of the heating process 
and the time of consumption of the milk. In New 
York City, the greater portion of the bottled mUk 
sold is of Grade B, most of which is brought to the 
city for pasteurization, which is done soon after mid- 
night. Much of this is delivered to the consumer 
the following morning, but a part is allowed to stand 
until the following day before deUvery. The city 
milk of Grade A was largely pasteurized in the conn- 



"DEFICIENCY" DISEASES 101 

try, and since they stored the milk for twenty-four 
hours after the heat treatment so as to insure a con- 
stant supply in case of delay in the dehvery from the 
country, there was an interval of forty-eight hours 
between the pasteurization and the delivery of the 
milk to the consumer. Hess reproduced these con- 
ditions in his institution by keeping milk pasteurized 
at 145° for forty-eight hours on ice. Of eight in- 
fants which were fed the milk so treated, two showed 
scorbutic symptoms, which were relieved by giving 
them orange juice. Two out of another eight which 
were fed milk which was kept on ice forty-eight 
hoiu-s after the heat treatment showed signs of 
scurvy. In other cases scurvy was observed in 
infants fed certified milk which had not been pas- 
teurized, when the latter had been kept on the ice 
forty-eight hours before feeding. Ageing is, therefore, 
effective in causing changes in both raw and pasteujv 
ized milk, so that the danger of the development 
of scurvy in infants to which it is fed is increased. 

Boiled milk has been extensively fed to infants in 
various parts of the world and in the experience of 
some observers does not induce scurvy. The expe- 
rience of Hess further supports the view that boiled 
milk is less liable to induce scurvy than is milk which 
has been pasteurized at 165° or at a lower temper- 
ature. Milk which has been pasteurized at 165° is 
more liable to induce scurvy than either boiled milk, 
or milk which has been pasteurized at lower temper- 
atures, as 140-145° for thirty nainutes. The most 



102 THE NEWER KNOWLEDGE OF NUTRITION 

satisfactory explanation for these results seems to be 
found in the bacteriological condition of the noilks 
treated in the various ways described. Heating milk 
at 165° kills nearly all the lactic acid forming bacteria 
which normally cause the souring of milk. Heating 
for thirty minutes at 140° to 145° leaves some of the 
organisms capable of development, and milk so pas- 
teurized wiU sour. In the absence of the acid formers 
there develop during the interval between heating 
and consumption the spore-forming organisms which 
are not killed by pasteurization. These -will, in time, 
cause the putrefactive decomposition of the milk. 
Any heat treatment which kills all the acid formers 
leaves the milk in a suitable condition for the devel- 
opment of the pernicious forms, and old nulk so 
treated may be a menace to the health of infants, 
and unfit for consumption by adults. Boiling tends 
to destroy all the organisms in milk and will do so 
if sufficiently prolonged. Such milk may be more 
suitable for food than that which has been so treated 
as to prevent souring and yet be hi a condition to 
permit the growth of putrefactive forms of bacteria. 
These results strongly support the view that there 
is a bacteriological factor involved ia the causation 
of scurvy, and emphasizes the importance of securing 
clean milk, and of having it so handled as to insiue 
its deUvery in a good bacteriological condition. 
MOk should iiot be kept in the home without efficient 
refrigeration, and should be consumed before it 
becomes stale. Pasteurization seems, in itself, to 



"DEFICIENCY" DISEASES 103 

have little influence in lowering the food value of 
milk. The stalen^s is the great element of danger. 
Pasteurization is desirable as a safeguard against 
such diseases as typhoid fever, tuberculosis, scarlet 
fever and such organisms as cause epidemics of sore 
throat. It does not render milk permanently harm- 
less. The public should insist upon having its miUc 
supply produced under hygienic conditions. Milk 
should then be cooled promptly so as to depress as 
far as possible the growth of the organisms which 
always find entrance through the air and from the 
cow and the milker. It should be carefully refriger- 
ated, and promptly delivered and properly cared for 
in the home, and should not be allowed to age un- 
necessarily before use. If pasteurized, it should pref- 
erably receive the lowest heat treatment which will 
effectively destroy the pathogenic organisms, and 
should be deUvered as promptly as possible there- 
after in a suitably cooled state. Stale milk is danger- 
ous, especially for use in infant feeding. 

Pellagra. — ^This disease has been common in parts 
of Europe for centuries. It is especially common in 
northern Italy, and has been sometimes referred to 
as Alpine scurvy. It is likewise known in Spain and 
anii the south of France. The disease was first ob- 
served in America in 1907, and has been steadily 
on the increase, especially in certain of the Southern 
States. In 1917 it was estimated that there were 
165,000 pellagrins in the United States. 

Pellagra is essentially a disease of poverty, al- 



104 THE NEWER KNOWLEDGE OF NUTRITION 

though there are many cases recorded among the 
well-to-do. It has been especially prevalent in the 
country, in villages, and in the poorer sections of 
cities, and is observed to occur most frequently 
following periods of scarcity of food. In Europe 
the disease was long associated with the consumption 
of spoiled maize as the chief article of diet, but it is 
now known that the eating of this grain has nothing 
whatever to do with .its causation. All observers 
are agreed that the diet is of primary import in the 
etiology of the disease, but differences of opinion 
stiU exist as to whether there is likewise a bacteri- 
ological factor involved. 

The trouble begins with digestive disturbances of 
ah indefinite character, followed by soreness of the 
mouth, which renders eating difficult, and a per- 
sistent diarrhea which saps the strength of the pa^- 
tient. Skin eruptions appear, and there are formed 
on parts of the body dark crusts which sometimes 
suppurate. In severe cases there are pronounced 
nervous disturbances preceding death. 

In its early stagps pellagra yields fairly readily 
to dietetic treatment'. Indeed it has been emphasized 
by clinicians that without dietary measures, there, is 
no effective treatment, and numerous cases are re- 
corded in which the disease has disappeared promptly 
when milk, eggs and meats, string beans, together 
with a liberal amount of the leafy vegetables, such 
as cabbage, collards, and lettuce, were included in 
the diet.i» 



"DEFICIENCY" DISEASES 105 

In the United States, especially, pellagra tends to 
seasonal occurrence, most new cases occurring ia the 
spring, or better, as Goldberger has emphasized, 
at the end of winter. JobUng, ia his excellent survey 
of pellagra in Nashville, found that nearly all cases 
had their onset ia the spring and early stmimer." 
It frequently happens that sufferers recover from 
their attacks of the disease during the later summer 
and fall, and suffer a relaspe during the following 
spring. Indeed the diet of many of the poorer people 
of the South, during the winter, consists principally 
of com bread, pork and molasses. From what has 
been said ia earUer chapters, it wiU be easily ap- 
preciated that such a combination of food-stuffs does 
not constitute an adequate diet, and it is significant 
that nearly all new cases develop after a hundred 
days or more of confinement to such a food supply. 

It should be pointed out that Jobling and Peter- 
son emphasize that from their observations the 
pellagrins, and the class from which the new cases 
develop, consume relatively much carbohydrate and 
relatively Uttle protein, since they make hberal use 
of com bread, com grits, and potatoes and biscuits 
made from bolted flour, . together with molasses. 
There were some who declared that they had regu- 
larly eaten eggs, butter milk, milk and meat. They 
f lusher point out that in the spring, s umm er and 
autumn months a great deal of green stviff in the 
fonn of turnip tops, wild mustard, green peas (seed) 
and green onions are eaten. The green onions are 



106 THE NEWER KNOWLEDGE OF NUTRITION 

eaten raw, the others cooked. In addition, during 
the summer months much fruit, especially peaches 
and apples, are eaten since these are usually cheap. 

In commenting upon the studies of Goldberger, 
JobUng and Peterson point out that the poorly nour- 
ished iadividual is prone to contract many diseases 
and their observation that there is a close relation- 
ship between the sanitary condition of the different 
parts of Nashville and the incidence of pellagra, 
tends to strongly support the view that the disease 
is associated with poor sewage disposal. The sani- 
tary conditions in those districts where pellagra is 
common are of the worst sort, in many instances 
there being little pretense made of doiag anything 
with the excreta, which during the summer is usually 
covered with flies. Screening was usually absent 
from those houses where the disease was found. 
Jobling and Peterson are essentially in accord with 
the conclusions of the Thompson-McFadden Com- 
mission ^ which made a thorough investigation of 
conditions in Spartanburg County, S. C, where 
pellagra is a scourge, and arrived at the conclusion 
that the disease is in some way related to a bacte- 
riological factor, and is probably distributed by an 
insect. 

Golderger has accomplished a great work in demon- 
strating that the diet, when properly constituted, 
causes the disappearance of pellagra, and prevents 
its recurrence. His dietary studies have demon- 
strated beyond a reasonable doubt that a faulty 



"DEFICIENCY" DISEASES 107 

diet is the most important factor in causing the de- 
velopment of the condition. He has shown that 
when liberal amoimts of milk and eggs and of meat, 
are introduced into the diet of institutions, such 
as insane asylums and orphanages, in which the dis- 
ease was previously common, they become free from 
it even though new cases are admitted freely and 
the sick are mingled with the weU. He and his co- 
workers have likewise made heroic attempts to 
transmit the disease to themselves by means of the 
administration of the raccreta and material from the 
lesions of pellagrins, but without success, when the 
experimenters were taking a satisfactory diet.^^ 

An ejcperiment on man, which was carried out by 
Goldberger, is of special interest. A diet consisting 
of dishes prepared from degerminated com meal, 
bolted wheat flour, rice, starch, sugar, pork fat, to- 
gether with sweet potatoes, cabbage, collards, turnip 
greens and coffee, induced the appearance of what 
were regarded as the incipient signs of the disease by 
the end of five and a half months in five of eleven 
men, who volimteered to submit themselves to this 
dietary r^gime.^^ 

Chittenden and Underhill ^* have described ex- 
periments in which dogs were restricted to a diet of 
crackers (wheat flour), cooked (dried) peas and 
cottonseed oil. After intervals varying from two to 
eight months, the animals developed the typical sore 
mouth, severe diarrhea and skin changes strikingly 
suggestive of pellagra in man. They were of the 

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108 THE NEWER KNOWLEDGE OF NUTRITION 

opinion that this diet caused these symptoms be- 
cause of the lack of some substance or substances of 
the class designated as "vitamines" by Funk. 

McCoUum, Simmonds and Parsons ^* demon- 
strated that the diet of Chittenden and UnderhUl, 
which consisted of bolted wheat flour, peas and 
cottonseed oil, cannot be deficient in any other uni- 
dentified dietary essential than the fat-soluble A, a 
l&ck of which is associated with the development of 
the eye disease, xerophthalmia. This conclusion is 
necessary since rats were shown to fail to grow or 
remaia in a state of health, on this mixture, and that 
it is rendered dietetically sufficiently complete by 
the addition of three types of purified food sub- 
stances, viz., mineral salts, protein, and fafc-soluble 
A, to induce growth at the normal rate. The animals 
failed, however, to successfully rear young. The 
first limiting factor is the inorganic content. Every- 
thing of an unknown chemical nature which the diet 
must contain is present in a mixture of wheat flour, 
peas and cottonseed oil, but there is a relative short-^ 
age of the fat-soluble A, which is abundant in cer- 
tain fats, and is associated with cellular structures 
generally in both animal and vegetable food-stuffs. 
McCollum, Simmonds and Parsons pointed out that 
although then" rats failed to maintain satisfactoty 
nutrition on this food mixture, unless the three 
' kinds of supplements were added, there was no 
soreness of the mouth or diarrhea, such as was ob- 
served by Chittenden and Underbill in dogs,^nd are 

\ i, A(; {; l.f 



"DEFICIENCY" DISEASES 109 

usually present in pellagra in man. The eyes became 
swollen when the diet was supplemented only by 
salts. 

An inspection of the diets described by Goldberger 
as common in those institutions where pellagra is 
prevalent, and the' winter diets of people in those 
districts where there is a high incidence of the dis- 
ease in the spring and summer months, shows that 
these are composed largely of seeds and seed prod- 
ucts, and the amoimts of leafy vegetables, milk, 
eggs and meat, are very small, or are entirely absent, 
for varyiag periods. McCoUum and Simmonds ^' 
have pointed out that in the experimental diet with 
which Goldberger reported having produced incipi- 
ent pellagra in man, about niaety-six per cent of the 
total solids of the food supply was derived from seed 
products: com meal, wheat flour, rice, starch, sugar, 
molasses and from pork fat, and only about four per 
cent from sweet potatoes and the leafy vegetables 
together. Such a small amount of the leaf does not 
suffice to make good the dietary deficiencies of the 
seed products ia such a diet. These deficiencies are 
now well understood, and it is further known that 
the tubers, such as the potato and sweet potato, are 
not so constituted as to serve as "protective" foods 
when taken together with seed products. The diets 
of those people who suffer from pellagra are, there- 
fore, deficient ia three respects. They are relatively 
low ia protein and their proteins are of relatively 
poor biological value, because they do not yield on 



110 THE NEWER KNOWLEDGE OF NUTRITION 

digestion, a favorable mixture of amino-acids for the 
transformation into body tissues. They lack a 
sufficient amount of the unidenti&ed dietary essential 
fat-solable A, and also of certaia mineral elements. 
The latter fault is ia most instances limited to a 
shortage of calcium, sodiiun and chlorine. Since it 
is the regular practice of naan to make additions of 
sodium chloride in the form of table salt, to his diet, 
the mineral deficiency in these diets may be said to 
be limited to the element calcium. Any one of these 
faults alone is sufficient to induce malnutrition when 
either the young or the adult animal is restricted to 
such diets as are common inpellagra stricken districts. 
Since, however, there seems to be good evidence 
that there sometimes occvir cases of pellagra in in- 
dividuals whose diets have included a certain amount 
of such articles as McCoUum and his co-workers 
have designated as PROTECTIVE FOODS, viz., 
milk, eggs and the leafy vegetables, the theory of 
an infection is supported. The prevalence of the 
disease in badly sewered districts supports this view. 
That there is a bacteriological factor involved in 
pellagra is further supported in some degree by the 
fact that McCoUum, Simmonds and Parsons ^' ob- 
served only malnutrition without diarrhea or sore 
mouth in rats fed diets which in the experience of 
Chittenden and Underbill produce ha dogs the gastro- 
intestinal symptoms seen in pellagra in man. The 
sloughing of the mucous membranes of the mouth, 
and the presence of ulcers in the intestine affords 



"DEFICIENCY" DISEASES IH 

conclusive evidence of an infection in their dogs. 
McCollum and co-workers found no unhealthy ap- 
pearance in the mucosa of the digfestive tract, even 
when their rats were moribund as the result of being 
fed only wheat flour, peas and cottonseed oil. It 
seems probable that the difference in this respect in 
the two species may well be attributed to a chance 
iofection in the one case which did not occiir ia the 
other. These observations are in harmony with the 
fact that not everyone who takes the poor diets de- 
scribed develops the disease. It seems logical in the 
light of aU the data available, to conclude that poor 
nutrition predisposes to iafection, and ftiat there is 
an infectious agent involved in the production of 
pellagra. There can be no reasonable doubt that 
the possibility that pellagra is a "deficiency" dis- 
ease, in the sense in which Punk employed this term, 
is definitely answered in the negative by the ex.- 
perimeatal work of McCollum and his co-workers. 

Rickets. — ^There can be no doubt that rickets is a 
nutritional disease, but its relation to the diet is not 
clear. It is characterized especially by an alteration 
in the growth of the bones. These become enlarged 
at the extremities and so soft that they bend under 
the stress of muscular contraction and xmder the 
weight of the body. It is a disease of the first two 
years of life, and is especially prevalent in children 
in whose diet milk is replaced too largely by cereals 
and other vegetable foods, not suited to the delicate 
digestive tract of the young child. Predisposing 



112 THE NEWER KNOWLEDGE OF NUTRITION 

factors in many cases are undoubtedly tuberculosis 
and syphilis. The symptoms develop gradually. 
Restlessness and 't)erspiration at night, great sen- 
sitiveness of the limbs, that even a light touch is 
extremely painful, are characteristic signs of the 
disease. There are gastro-intestinal disturbances, 
especially colic and distension of the intestine with 
gas, so that the abdomen protrudes. The bones 
become thickened, and nodules develop at the junc- 
tures of the ribs with the costal cartilages, forming 
the characteristic "beaded" ribs. There is defective 
ossification of the skull; the teeth appear later than 
noHnal and in unusual order. Various deformities 
of the head, spine, chest and limbs result as the child 
develops. Recovery with deformity is of frequent 
occurrence. 

There must, at the present time, be an element of 
speculation in any discussion of the relation of diet 
to rickets. The well-known deficiencies from the 
dietary standpoint of the cereal grains and the other 
storage organs, together with the injury to the in- 
testine, which is nearly always present, as shown by 
the distended abdomen, and the occurrence of 
rickets only in early life, and so frequently in associa- 
tion with infectious disease, all make it unnecessary 
to invoke the aid of any hypothetical "vitamine," 
to a lack of which the disease may be attributed. 

Hess ^^ has recently described the results of his 
dietary studies among the negro women of the 
Colimibus Hill district in New York, whose children 



"DEFICIENCY" DISEASES 113 

almost all suffer from rickets. It is significant that 
these women are attempting, like the very poor in 
many cities, to Uve on a diet derived from the en- 
dosperm of wheat, maize and rice, bolted flour, 
degerminated commeal, polished rice, together with 
tubers and meats. It will be evident from the data 
furnished by the application of the biological method 
for the analysis of food-stuffs, which McCollum and 
his co-workers have perfected, and which was de- 
scribed in Chapters I to III, that there are no com- 
binations of those food-stuffs tvhose functions are 
those of storage organs, which will constitute a satis- 
factory diet for growth. Muscle tissue does not tend, 
except in respect to the protein factor, to correct the 
dietary faults of such naixtures. The regular con- 
sumption of such diets will in the course of a few 
months cause a distinct lowering of the vitality of 
an adult and wiU cause even greater injury to the 
young child. In a later chapter it wiU be shown that 
the milk of mothers taking such diets does not 
satisfactorily nourish the young. 

What has said been above regarding the special 
dietary properties of the different food-stuffs which 
go^to make up the diet of civiUzed man, and the 
dietary habits of those classes of people who suffer 
from the diseases which have come to be recognized 
as being due to faulty diet, make it easy to see that 
there has become fixed in the minds of students of 
nutrition and of the reading public, an altogether 
extravagant idea regarding the importance of the 



114 THE NEWER KNOWLEDGE OF NUTRITION 

substances to which Funk gave the name "vita- 
mines." Of the diseases which Funk considered due 
to lack of unidentified substances of this nature, 
viz., beri-beri, scurvyff)ellagra and rickets, but one, 
beri-beri, has been shown to be due to this cause. 
In the course of the analysis by McCoUum and Davis, 
of the problem of what chemical complexes are nec- 
essary to constitute the simplest diet which will 
serve to support growth in the young, and maintain 
physiological well-being in the adult, a second dietary 
"deficiency" disease in the same sense as beri-beri, 
was discovered, and shown to have occurred sporad- 
ically in man. This is the type of xerophthalmia 
which results from a deficiency of the dietary essen- 
tial of unknown chemical nature, fat-soluble A. 
Beri-beri is due to the lack of the second unknown 
dietary essential water-soluble B. Pellagra, scurvy 
and rickets do not belong in the same category with 
beri-beri, and there do not exist "curative" sub- 
stances of unknown nature for these diseases. The 
individual is predisposed to the development of these 
syndromes by faulty diet, but the faults have been 
shown by the biological method for the analysis of 
the individual food-stuffs or their mixtures, to reside 
in maladjustments, and unsatisfactory quantitative 
relationships among the now well-recognized con- 
stituents of the normal diet. They are to be sought 
in the quaUty and quantity of the protein, the char- 
acter and amount of the inorganic constituents, the 
physical properties of the residues which are left 



"DEFICIENCY" DISEASES 115 

after digestion, and form the feces from whicli the 
intestine must rid itself. It seems probable that 
the only imidentified substance which is physiolog- 
ically indispensable, which is not sufficiently abun- 
dant in the diets employed by the people of the 
United States and Europe where there are used ia- 
sufficient amounts of milk, butter, cream, eggs and 
the leafy vegetables, is the fat-soluble A, but occa- 
sionally diets may be met with which contain too 
Uttle of the water-soluble B. Sufficient knowledge is 
now available to make it possible to select such foods 
as will mutually make good each other's deficiencies, 
and to combine them in such proportions as will 
insure the disappearance of all the diseases of man 
which are brought on by faulty diets. The same 
knowledge will, in the future, make possible an 
efficient utiUzation of feeding-stuffs for animal pro- 
duction, which will be of iuestimable economic 
value to mankiad. 



CHAPTER VI 

THE NURSING MOTHER AS A FACTOR OF SAFETY IN THE 
NUTRITION OF THE SUCKLING 

Anyone who reflects upon the relation of the. 
mothej" to her young during the suckling period, 
must maxvel at the fact that during early life the 
young mammal cannot thrive on the diet of the 
adult. It must have milk for a shorter or longer 
period after birth. This the lactating animal is able 
to form from her food through the agency of the 
mammary gland. The period of dependency varies 
greatly in different species. Among mammals, 
with which the author is familiar, the young guinea 
pig is bom in the most highly developed state. The 
newborn cavy is capable of eating grass or succulent 
vegetables during the first or second day of post- 
natal life. The young rat may be safely weaned at 
the age of twenty-five days, provided a highly satis- 
factory diet of the type which sufficies for the adult 
is then supphed. The young pig (swine) becomes 
able to eat fairly Hberally of the normal adult diet 
at the age of six or eight weeks, whereas the humaij 
infant must live largely on a mUk diet during the 
first year of fife and should have a liberal allowance 
of milk and of eggs during the entire growing period. 

116 




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THE NURSING MOTHER 117 

Even eggs will not entirely replace milk diiring any 
part of this period. It is of great importance that 
we should miderstand the relationship between the 
character of the diet of the lactatiag female, and the 
quahty of the milk which she is able to produce. 
Our knowledge of this subject is still very incomplete, 
but experimental studies on animals have recently 
thro^vn light on certain very important phases of 
this problem. 

In order to gain information on the ^lation be- 
tween the character of the diet of the mother and 
the value of the milk which she produces, McCollum . 
and Simmonds ^ carried out a series of experiments 
on lactating rats, whose diets were faulty in known 
ways, and observed the effect on the growth of the 
yo\mg which these mothers nursed. The mothers 
were fed a highly satisfactory diet until they had 
completed their term of pregnancy. As soon as the 
yoimg were born, the litter was in all cases reduced 
to four, ia order that the nutritive undertaking of 
the mother should ia no case be bxirdensome. The 
mother was at once restricted to a diet which would 
not iaduce any growth whatever in a yoimg rat after 
separation from the mother at weaning time. The 
diets of the mothers in the various experiments were 
faulty in respect to each of the factors which are 
necessary for the fornaation of a "satisfactory diet, 
but the nmnber of characters in which a single diet 
was faulty varied from one to three. 

In one case the mother was fed upon a diet of 



118 THE NEWER KNOWLEDGE OF NUTRITION 

purified proliein, carbohydrate (dextrinized starch), 
a stiitably constituted inorganic salt mkture, and 
an alcoholic extract of wheat germ to furnish the 
unidentified dietary essential, water-soluble B. This 
diet contained everything necessary for the nutrition 
of a young rat during growth, except the fat-soluble 
A. The problem was to find whether the mother 
could, through the agency of the mammary gland, 
form the missing substance, fat-soluble A. Expe- 
rience has ghown that the young animal after the 
weaning age, cannot produce it de novo, for its own 
preservation from any of the other constituents of 
its food. The results of the experiment indicated 
that the quantity of the fat-soluble A in the milk 
produced from such a diet is below the amount 
necessary for the promotion of the maximum rate 
of growth in the young. It has been shown by 
Osborne and Mendel,^ that the body fats of beef 
cattle contain a small amount of the fat-soluble A. 
It seems certain that the body fats of an animal 
which has been fed for some time on a diet rich in 
this substance, will serve as a reserve supply of this 
dietary essential, which the mother can secrete into 
the milk. In other experiments, Chart 15, definite 
evidence is presented that this substance is not 
abundant in the milk unless it is present in the diet 
of the mother. The presence of some fat-soluble A 
in the tissues of the mother makes it especially difi&- 
cult to 'obtain milk which is entirely free from this 
substance. 



THE NURSING MOTHER 119 

Through similar experiments with diets which 
contained the fat-soluble A, but not the water- 
soluble B, evidence was secured that for a time the 
mother is able to secure this dietary factor from her 
reserve supply, but none of the growth curves ia- 
dicated that the substance is present in the milk 
in adequate amount when the diet of the mother 
lacks it. It seems certaia that neither of these 
substances is present in abimdance in the milk of 
the mother, imless it is furnished in her food. 

Evidence confirmatory of this view is found in 
the studies of Andrews ' on infantile beri-beri. It 
is well known that the faulty diet of rice and fish, 
which furnishes the principal food of many of the 
poorer classes of the-Orient, does not prevent the 
onset of beri-beri, and infants who nurse mothers 
who are suffering frofa-the-disgase^ likewise develop 
beri-beri. Andrews iaduced several Filipino women 
whose infants had just died of beri-beri, to nurse 
young pups, and noted that in all cases the lat- 
ter failed to grow, became edematous, and lost 
the use of their hind legs. Paralysis of the posterior 
extremities is one of the symptoms of the disease in 
man. It is evident that in the milk of these mothers 
there was a shortage of the water-soluble B, for it 
is a shortage of this substance which causes the 
development of this syndrome. 

It has been pointed out that young animals do 
not grow when confined to a single seed or mixture of 
seeds of plaaits, for the reason that these are all 



120 THE NEWER KNOWLEDGE OF NUTRITION 

lacking in sufficient amounts of the inorganic el- 
ements, calcium, sodium and chlorine, and are too 
poor in the fat-soluble A to support normal nutrition. 
The quality of their proteins is likewise too poor 
to make them very satisfactory for the support of 
growth. McCoUum and Simmonds have studied 
the extent to which the mother is able to produce 
milk of satisfactory character for the promotion of 
growth in the yoimg, when confined to a single seed as 
the sole source of nutriment. Charts 15 and 16 show 
the effects of such diets on the growth of the young. 
The curves of rat 211 and of her litter of four 
young (Chart 15) illustrate the remarkable growth 
which a mother rat is able to induce in her young 
when her diet is highly satisfactory, and while 
doing so, she is able to increase her own weight very 
appreciably. In marked contrast to this "normal" 
accomplishment stands the failure of rat 738 to in- 
duce more than one-third the normal rate of growth 
in her young when restricted to rolled oats as her 
sole food supply. The drop in the curve of the 
young at the 40th day was the result of the death 
of the young at brief intervals. The mother lost 
weight regularly, showing that she was sacrificing 
her own tissues for the preservation of her young. 
Rolled oats, like the other seeds, require improve- 
ment in respect to three dietary factors before it 
becomes a complete food, and on such a faulty diet 
the mother produces milk which is not satisfactory 
for the promotion of growth in her offspring. 



THE NURSING MOTHER 121 

Rat 843, whose diet consisted of rolled oats sup- 
plemented with fat-soluble A (as butter fat) induced 
growth in her young at a somewhat greater rate than 
she could have done, had she eaten oats alone, and 
was able to keep them aUve for a longer period. 
The first one died on the 57th day and the others 
followed in rapid succession. This mother lost con- 
siderable weight up to the time "that the young began 
to eat of the oat and butter fat diet. Young rats, 
after removal from the mother, cannot grow at all 
on this diet. 

Rat 899, was fed a diet of rolled oats to which was 
a;dded such an inorganic salt mixtm-e as made good 
the mineral deficiencies of the oat kernel. Her diet 
was stUl deficient in fat-soluble A, and to some extent 
in the quality of its proteins. With this food her 
milk was of distinctly better quality than that which 
can be produced on a diet of oats alone, or on oats 
supplemented with fat-soluble A, or on oats supple- 
mented with purified protein (rat 948). From these 
results it is apparent that the first limitiag factor 
of the oat kernel for milk production in the lactating 
animal is the same as in the young for growth, viz., 
the inorganic content of the food supply. 

The importance of having the inorganic content 
of the diet properly constituted is shown especially 
well in the performance of the mothers 983 and 
1978. The former was fed roUed oats supplemented 
with both fat-soluble A, in the form of butter fat, 
and purified protein in the form, of casein of milk. 



122 THE NEWER KNOWLEDGE OF NUTRITION 

Even with these two additions she was able to induce 
less than half normal growth in her young and they 
began to die at the age of 45 days, and all succumbed 
in rapid succession. Rat 1978, on the other hand, 
whose diet consisted of rolled oats supplemented 
with a suitable salt mixture and butter fat, was able 
to induce growth in her yo\mg at about two-thirds 
the normal rate. The improvement of the milk 
by the inclusion of fat-soluble A in the diet is very 
apparent, since the young did not die during the 
period of sixty days covered by the experiment, and 
supports the view that this substance cannot be 
synthesized by the mother. 

Rat 1019, whose diet consisted of rolled oats 
supplemented with purified protein and a suitable 
salt mixture, shows that the mother is able to induce 
nearly the optimum rate of growth in her young dur^ 
ing a period of thirty days, although her diet was very- 
poor in the factor fat-soluble A. It should be borne 
in mind that the seeds, because they contain a small 
proportion of cellular structures in addition to their 
reserve food package in the endosperm, contain a 
small but inadequate amount of the fat-soluble A. 
The mother is able, when the diet of oats is corrected 
with respect to two factors, protein and salts, to 
concentrate in the milk the small content of the fat- 
soluble A which her diet suppUes. She is probably 
also able to draw in some degree upon her small 
store of this substance which is deposited in her body 
fats, and supply the young with enough of it to 



THE NUESING MOTHER 123 

enable them to reach a state of relative independence, 
which in a wild state would enable them to go in 
search of food for themselves. There is abundant 
experimental proof that when the protein and in- 
organic content of the food are of highly satisfactory 
character, animals can subsist for a long period on a 
supply of fat-soluble A too small to prevent the onset 
of xerophthalmia in diets of lower biological value. 

These records of niu-sing mothers and their young 
make it apparent that the former is limited in a 
general way in the utihzation of food for milk pro- 
duction, in the same maimer as in the growing yoxmg 
in the utilization of food for the construction of new 
body tissues. She is, however, a factor of safety for 
her yoimg in no small degree. It should be remem- 
bered that a young rat cannot grow at all when, 
after the weaning age, it is limited to the oat kernel, 
or to the oat kernel supplemented with either salts, 
protein or fat-soluble A alone, or on a diet of oats 
supplemented with both protein and fat-soluble A. 
In order that it may grow even very slowly it is 
essential that both a suitable salt mixture and fat- 
soluble A shall be added to the oat kernel. It can- 
not grow normally unless the protein factor is hke- 
wise improved. In the records of the mothers and 
young shown in Chart 15, the young continued to 
grow in certain instances after the twenty-fifth day, 
the age at which they may be safely ' weaned when 
their milk supply has been of normal composition. 
This fact is conclusive evidence that even after the 



124 THE NEWER KNOWLEDGE OF NUTRITION 

young become able to eat of the diet on which the 
mother had produced the milk on which they were 
able to grow — ^a diet on which they would be unable 
to grow at all without some corrections and improve- 
ments — ^they were still receiving a supplementary 
milk supply from the mother. This served to correct 
in some measure the faulty diet of oats plus an in- 
complete supplementary addition. It seems certain 
that irdlk production must have been very con- 
siderable in amount, to thus enhance the diet of 
four young whose weight collectively was about half 
that of the mother herself. 

The inorganic content of all the seeds is the first 
limiting factor in preventing growth in young ani- 
mals, and in determining the quality of the milk which 
can be produced from them. The young animal 
cannot grow at all on seeds unless one of the factors 
corrected includes certain salt additions, yet the 
mother is able to produce milk without any such 
additions, which is capable of inducing a limited 
amoimt of growth in the young. It is apparent that 
one of her most important relations to her helpless 
offspring is her capacity to supply it with a better 
inorganic food supply than she herself secures in her 
food, when the latter is of poor quality. 

The growth curves of the young of mothers whose 
diets consisted of the oat kernel without and with 
pxu"ified food additions, illustrate likewise very well 
the results which are observed when similar ex- 
periments are conducted with the wheat or maize 



THE NURSING MOTHER 125 

kernel. They emphasize the fact that for milk pro- 
duction as for growth, the seeds of plants may be re- 
garded as closely similar in their dietary properties. 
It is therefore, rendered highly probable that the 
same analogy runs through the series of food-stuffs 
in their value for the production of milk of normal 
character. We are not to expect, therefore, that a 
diet consisting of even a complex mixture of seeds, 
tubers and roots, will produce milk of highly satis- 
factory character, and without undue strain on the 
mother. It has been emphasized that even this list 
of foods of the class whose functions are those of stor- 
age organs, do not suffice even when combined with 
meat, to induce satisfactory growth in the young. 
It follows as a logical conclusion, that a lactating 
mother will not be able to produce milk of a very sat- 
isfactory character when she is restricted to such 
food-stuffs. It should be reiterated that there are 
two classes of food-stuffs which are so constituted as 
to correct the deficiencies of seeds, tubers, roots and 
meat. These are milk and the leaves of plants and 
they should be used very Uberally in the diet. Eggs 
are in some degree to be regarded as comparable to 
these, but eggs have not the favorable mineral con- 
tent of the leaves and of milk, and this is one of the 
most important factors in which the storage organs 
of plants need supplementing. 

The question wiU arise in the minds of many, as 
to whether the inability of the young to grow on the 
milk produced by mothers which were Uving upon 



126 THE NEWER KNOWLEDGE OF NUTRITION 

an inadequate diet, was not the result of the failure 
of the mothers to produce enough milk rather than 
mUk of abnormal composition. It has not been 
found possible to secure complete information as to 
the actual amount of milk which these rats secreted, 
but we have analogous data from domestic animals, 
which support the view that milk secretion remains 
fairly constant in the lactating animal even under 
very unfavorable conditions of nutrition. 

Babcock * has described experiments in which he 
deprived cows of common salt during lactation, 
other than that which they secured in their regular 
ration, which was of a type suitable for the dairy- 
cow. The keen appetite of the herbivora for salt is 
a matter of common knowledge. Deer which are 
very shy will risk any danger to secure salt at their 
accustomed Kcks or from salt springs. The periods 
of salt deprivation varied from two to fifteen months, 
and some of the animals actiially died, and others 
were saved from death by the administration of salt. 
In no instance was there a notable decrease in the 
yield of milk by these cows up to a short time be- 
fore they began to fail rapidly. Indeed the fat con- 
tent of the milk of the cows receiving an inadequate 
salt supply was slightly higher than in the milk of 
the control group. 

Eccles and Palmer ^ have conducted a very thor- 
ough experimental study of the influence of under- 
feeding of cows on milk production, and have studied 
its €omposition in cows whose rations were of suitable 



THE NURSING MOTHER 127 

composition, but inadeqtmte in amount. These 
results show that cows were able, during the early 
part of the lactation period, to maintain the milk 
flow undiminished for forty days, when receiving 
but 75 per cent enough food to meet her require- 
ments. Under such conditions of nutrition there 
was no pronounced change in the composition of the 
milk. During the latter part of the lactation period 
there was some falling oJEf in nulk production as the 
result of under-feeding. 

Ducaisne ^ in 1870, noted that during the siege of 
Paris, yoimg and vigorous women were able to pro- 
duce enough milk to maintain their infants, and in 
some cases to increase their weight when they were 
partially fasting. These observations, as well as 
those of Andrews on women whose infants had died 
of beri-beri,' all support the view that under con- 
ditions of faulty nutrition, it is the quality of the 
milk rather than the quantity which early suffers 
impairment. Dr. Manuel Roxas, of the College of 
Agriculture of the PhiUppine Islands, has informed 
the author in a private commimication, that the in- 
fants' death rate among the natives is much higher 
in the breast-fed than among the bottle-fed children. 

The occurrence of infantile beri-beri, rather than 
of death from starvation, further serves to demon- 
strate that it is milk of poor quaUty, rather than 
lack of sufficient amount of milk which is responsible 
for the high infant mortahty in those parts of the 
world where the poorer classes live too largely on 



128 THE NEWER KNOWLEDGE OF NUTRITION 

food-stuffs derived from products whose biological 
functions are those of storage organs, and meat. 

The statement which one sees reiterated so fre- 
quently, that breast feeding of infants is superior to 
the best system of artificial feeding, needg to be 
qualified to some extent. There are, without ques- 
tion, in many parts of the world, large groups of 
people whose diets are of such a character that the 
quaUty of the milk produced by the lactating mother 
is not such as to make it a satisfactory food for their 
iafants. It should be thoroughly appreciated that 
the human mother should have in her diet a Uberal 
amount of milk in order to safeguard the health and 
well-being of her infant, and of leafy vegetables, 
which serve the two-fold function of a protective 
food and of greatly aiding intestinal elimination. 
That some mothers can induce a fair amount of 
growth in their infants while taking a faulty diet, 
cannot be denied, but that both mother and child 
suffer impairment as the result is beyond question. 
It is not enough that the diet shall furnish enough 
calories and enough protein, and shall afford variety 
and palatabiUty. The pecuUar dietary properties 
of the food-stuffs which enter into the diet are of 
paramount importance, and must be taken into con- 
sideration. 

Attention should again be directed to the observa- 
tions of Hess' that the diet of the negro women of 
the Columbus Hill district in New York, whose diets 
are derived almost exclusively from seed products, 



THE NURSING MOTHER 129 

tubers and meats, fail to nourish their infants satis- 
factorily as shown by the almost universal prevalence 
of rickets among the latter. It is difficult for man 
to correct the dietary deficiencies of these products 
by the use of the leaves of plants as his sole protective 
food, because of the limited capacity of his digestive 
tract. Milk in liberal amounts should always be 

included in the diet of the lactating mother. '"' 

■ "ki 



CHAPTER VII 

PRACTICAL CONSIDERATIONS WHICH SHOTJID GUIDE IN 
THE PLANNING OF THE DIET 

In the preceding chapters there were presented 
data, which have been obtained by biological 
methods, concerning the special dietary properties 
of the several classes of natural food-stuffs, which 
enter into the diets of man and animals. It is evident 
from the experiments described that a diet may fur- 
nish an abimdance of protein and energy, and may 
be easy of digestion, and may furnish a wide variety 
and include several seeds or products derived from 
these, together with tubers, roots and meats, and 
may be highly acceptable to the human palate and 
yet fail utterly to support satisfactory nutrition. 
In the light of such facts, it becomes apparent that 
a chemical analysis of a food-stuff throws no light 
whatever upon certain aspects of its dietary prop- 
. erties. It is only by biological methods that we can 
arrive at principles which can serve as a safe guide as 
to the method of procedure by means of which safe 
diets can be planned. In the present chapter will be 
discussed a number of questions which always arise 
in the minds of those who wish to apply the new 
knowledge to the planning of a suitable dietary 
regime. 

130 



THE PLANNING OF THE DIET 131 

It should be understood that it is neither necessary 
or desirable that we should abandon the customary 
classification of food-stuffs on the basis of chemical 
composition. We must have a language of nutrition, 
and consider foods on the basis of their protein, 
carbohydrate, fat, water and mineral content, as we 
have always done. We should be familiar with the 
quota of energy available from the different types of 
foods. We must, however, take into consideration 
certaia facts which have not hitherto been considered, 
and concerning which a chemical analysis gives no 
information. 

One of the outstanding results of modem research 
in nutrition is the great difference in the biological 
values of the proteins from different sources. In a 
general way this is appreciated by all well informed 
teachers of the present day, but many are still in 
need of clearer distinctions regarding what data in 
the literattire are capable of direct apphcation to 
practical nutrition, and what are of such a nature 
that they cannot be so applied. No lack of apprecia- 
tion is intended of data of the latter type, for they 
may have, and indeed frequently have a value of 
the first importance to the investigator in this field. 
As an example may be cited the laborious studies 
through which the amino-acids became known, and 
the data jdelded by such method of analysis of the 
proteins as those of Fischer and of Van Slyke. Im- 
portant as are these results in making possible fur- 
ther progress, they are not of such a character that 



132 THE NEWER KNOWLEDGE OF NUTRITION 

they can be applied, as has been frequently at- 
tempted, in making deductions concerning com- 
parative food values. It is, however, through such 
studies that we have arrived at a satisfactory working 
hypothesis concerning the nature of the proteins, 
and have become able to appreciate why the proteins 
have different values in nutrition. Our analytical 
methods do not make possible an approximately 
quantitative determination of more than a third of 
the total number of the digestion products of the 
proteins. An attempt to utilize the figures for the 
yield of this or that amino-acid by one or another of 
the proteins, as evidence of the comparative values 
of the proteins themselves, or of the food-stuffs from 
which they are derived, will lead to entirely fallacious 
deduction. 

Such data as are tabulated in the Uterature for the 
yields of the different amino-acids, make the pea 
and bean proteins appear superior to those of the 
cereal grains. McCoUum and Simmonds have re- 
ported a long series of experiments with diets so 
plaimed that they were adequate in aU respects, 
and the protein content was derived entirely from a 
single seed. The amount of protein in the diet was 
varied so as to find in one series what was the lowest 
per cent of protein in the food mixture which would 
just maintain a grown rat over a period of several 
months without loss of body weight, and in another 
series, the minimum amount of protein was deter- 
mined which would induce in the young, half normal 



THE PLANNING OF THE DIET 133 

and full nonnal rate of growth respectively. The 
data regarding the values of several of the more im- 
portant seed proteins for maintenance are of great 
interest. Rats can be maintained in body weight 
on suitably constituted diets containing 4.5 per cent 
of oat protein, or of miUet seed protein; on 6 per cent 
of maize, rice or wheat proteins; on about 8 per cent 
of flax-seed protein, whereas it requires about 11 to 
12 per cent of the proteins of the pea or the bean to 
accompUsh the same result. 

Chemical analysis shows the proteins of the pea 
and bean to contain all the known amino-acids, 
and none of these are present in excessive or in min- 
imal quantities, whereas the wheat and maize pro- 
teins yield excessive amoimts of one of them in par- 
ticular. Glutamic acid, one of the digestion products 
of proteins, is present in the proteins of the muscle 
tissues of animals, in the case of no less than half a 
dozen species, to the e;:tent of twelve to fourteen 
per cent. The same acid is, present in the two prin- 
cipal proteins of the wheat kernel to the extent 
of nearly 40 per cent, and in the principal protein 
of the naaize kernel to the extent of about 25 per 
cent. These proteins show other differences in com- 
position which led to the behef that they were of 
relatively low biological value for growth, before 
they were studied satisfactorily by appropriately 
planned feeding experiments, all of which have con- 
firmed this view. The observation that the split 
pea and navy bean proteins are of much less value in 



134 THE NEWER KNOWLEDGE OF. NUTRITION 

nutrition came therefore as a distinct surprise, since 
these results were not what were expected, in view 
of the tabulated yields of the several amino-acids 
shown by the most careful chemical analysis. The 
data obtained, by properly planned feeding experi- 
ments are highly reliable, those from the chemical- 
analysis very unsafe, from which to draw deductions. 
It should be understood that these values for the 
proteins of the seeds apply only to the proteins of 
the single seed when fed as the sole source of protein. 
When fed in mixtures of two or more proteins having 
individually low values for the support of growth, they 
may mutually make good each other's amino-acid 
deficiencies, and form a mixture which is better than 
either constituent when fed singly. Since this was 
to be expected, McCoUum, Simmonds and Parsons 
have made many feeding trials with simple com- 
binations of two seeds, such as two cereal grains, one 
cereal and one legume seed (pea, bean) ; one seed and 
one leaf, etc., as the sole source of protein in the diet, 
and have sought to find which are the most fortunate 
combinations of the most important food-stuffs for 
the production of protein mixtxires of high biolog- 
ical values for the support of growth. These trials 
have shown that, while such mixtures of proteins are 
superior to the individual foods fed separately as 
sources of protein, it has not been found possible to 
obtain protein mixtures from vegetable sources which 
even approximate the value of milk proteins, for the 
support of maintenance or growth. 



THE PLANNING OF THE DIET 135 

The mtrogen-contaiiiing compounds of the potato 
have been lauded by several investigators as being of 
extraordinary value as a source of protein. Mc- 
CoUum, SimlQonds and Parsons have studied the 
proteias of the potato, both for maintenance and 
growth, in experiments in which this tuber served as 
the sole source of protein, and all its dietary defi- 
ciencies were made good by suitable additions of 
purified food substances. These aU indicate that 
when fed as the sole source of protein, the nitrogen 
compounds of the potato have a distinctly lower 
value than have the proteins of the cereal grains, 
oat, wheat, rice and maize. 

Enough has been said regarding the great dif- 
ferences in the values of the proteins from different 
sources, to make it clear that it is impossible to say 
how much protein the diet should contain without 
having a knowledge of the values of the proteins 
which the diet contains. Chemical methods of 
analysis are not yet sufficiently perfected to throw 
any appreciable fight on the values of the mixtures 
of proteins which occur in our natural foods. 

The great attractiveness of the "vitanaine" hy- 
pothesis of Funk, as an explanation for all the states 
of malnutrition which are referable to faulty diet, 
has led, in recent years, to much discussion of the 
question of the possible deterioration of foods during 
cooking, canning and drying. The demonstration 
by McCollum and his co-workers that there are but 
two imidentified dietary essentials, and but two diet- 



136 THE NEWER KNOWLEDGE OF NUTRITION 

ary "deficiency" diseases, due respectively to a 
shortage of one or the other of these substances, fat- ' 
soluble A and water-soluble B, and that there are no 
"growth determinants" unnecessary for the maiate- 
nance of health in the adult, does not minimize the 
importance of this subject. The work of a ntunber 
of investigators has shown that the water-soluble B, 
the protective substance against beri-beri, is readily 
destroyed when an excess of even such weak alkalies 
as soda are added to the food, suggests that this 
substance may be of an unstable character. 

Osborne and Mendel ^ have shown that butter 
fat may have a blast of steam passed through it for 
two hours and still retain its peculiar growth-pro- 
moting properties, due to the presence of the fat- 
soluble A. This observation is in harmony with 
those of McCoUum and Davis, that heating butter 
fat at the -temperature of boihng water does not 
affect its peculiar dietary value. It is apparent, 
therefore, that any conditions to which milk fats are 
liable to be subjected during the cooking of foods 
will not greatly alter its value as a source of the fat- 
soluble A. McCoUum andSimmonds have recently 
(unpublished data) tested a sample of butter fat 
prepared from evaporated milk, furnished to them 
by Dr. Lucius P. Brown of New York City, and have 
found it very effective in relieving the xerophthalmia 
in rats, brought on by the lack of the fat-soluble A 
in their diets. It appears, therefore, that there is no 
great deterioration in the quality of milk fats brought 



.THE PLANNING OF THE DIET 137 

about by the processes of removal of water in the 
preparation of condensed or evaporated milks. They 
have likewise shown, as have also Osborne and Men- 
del, that dried milks still contain the fat-soluble A 
in abundance. There can be no serious objection to 
the use of dried or canned milks on the basis of their 
value with respect to this dietary essential. 

The situation is likewise quite clear with respect 
to the ordinary dried foods. Leaves such as celery 
tops and those of the immature alfalfa plant, when 
dried in the ordinary way, are still good sources 
of the fat-soluble A. The alfalfa leaves were dried 
in the sun and the celery tops by artificial heat ia a 
current of air after a preliminary treatment with 
steam. 

McCoUum and Davis * have pointed out that 
wheat germ can be moistened and heated in an auto- 
clave at fifteen pounds pressure for an hour or more 
without any extensive destruction of the water- 
soluble B, and McCoUum, Simmonds and Pitz ^ have 
subjected soaked navy beans to similar treatment 
without causiag any great deterioration with respect 
to this dietary factor. This treatment is comparable 
to that to which fruits and vegetables are subjected 
when processed in canning, and shows that the wide- 
spread belief that canned foods have lost these diet- 
ary essentials is, at least, generally without foim- 
dation. The cooking of beans or greens with the 
addition of soda, which is a conmion practice, may 
cause the destruction of one or both of the unidentified 



138 THE NEWER KNOWLEDGE OF NUTRITION 

dietary essentials. At least in the case of the water- 
soluble B, this will probably be true if sufficient 
soda is added to render the food alkaline. The use 
of soda in biscuit making will, according to Voegtlin, 
and Sullivan * cause the destruction of the water- 
soluble B, for they found that corn naeal cooked with 
soda was no longer effective in causing the "cure" 
of beri-beri in pigeons. 

In this connection it should be borne in mind that 
our brdinary foods all contain several times the 
amount of the water-soluble B which is necessary 
for the maintenance of growth and health in animals. 
There seems to be no vahd reason why, if it is neces- 
sary for cuhnary purposes, to use soda in the cook- 
ing of a few foods, the practice should be discontinued. 
If the diet is so planned as to furnish a suitable quota 
of milk, and of cereals and other foods which are not 
so treated as to destroy the water-soluble B there is 
no danger of a shortage of this substance in the diet. 
It is now well demonstrated that with the diets employed 
in Europe and America there is no such thing as a 
"vitamine" problem other than that of securing an 
adequate ariiount of the substance fat-soluble A. Seeds 
and their products, tubers, roots and meats in the 
amount in which they are ordinarily consumed, do 
not furnish enough of this substance for the mainte- 
nance of an optimum state of well-being. Diets com- 
posed of these substances exclusively, may, when 
their other deficiencies are corrected, contain enough 
of the fat-soluble A to induce fairly good growth to 



THE PLANNING OF THE DIET 139 

nearly the full adult size, and may lopg prevent the 
development of xerophthalmia. They do not supply 
enough of it to support maximum vigor over a long 
period, and fall short of the amoimt necessary under 
the special conditions involved in pregnancy and 
lactation. 

There is a wide-spread belief that wheat is superior 
to the other cereals as a food. There is no experi- 
mental evidence that this is true. Rye, barley, oats 
and maize resemble wheat very closely in their diet- 
ary properties, and it is safe to say that these can 
entirely replace wheat in the diet of children, adults 
and iavahds without the least detriment to health. 
Those who have become accustomed to the use of 
wheat bread, are attached to it principally because 
of habit. Dietary habits become very firmly fixed 
and are hard to break away from. Millions in the 
Orient are greatly attached to rice as a food, and 
feel that they cannot hve without it, whereas, we ia 
America cannot bring ourselves to eat Uberally of it 
in the simple and unappetizing form in which it is 
entirely acceptable in the Oriental. The Italian 
feels that no diet is satisfactory unless it contains 
macaroni. Garhc and other flavors which appeal to 
the appetite of certain peoples are disliked by others. 
These prejudices and many others are not expressions 
of physiological need, but are piu-ely demands for 
something to which we have become accustomed. 
When properly cooked, cormneal, oats and other 
cereals have never been shown to produce digestive 



140 THE NEWER KNOWLEDGE OF NUTRITION 

disturbances. .Reports that the people of Belgium, 
when restricted lo the scanty fare which could be 
furnished them after the occupation of their territory 
by Germany, suffered from digestive disturbances 
from eating com bread, are not to be taken as evi- 
dence that the corn products were in themselves re- 
sponsible for the trouble. They were the sequel of 
an inadequate diet which impaired the vitaUty. 
Experiments have been described, showing that 
bolted wheat flour is inferior to whole wheat. ^- If 
two pigeons are fed whole wheat and bolted flour re- 
spectively, while a third is allowed to fast, the first 
will remain in a state of apparent health for several 
weeks, the second will lose weight and die earUer than 
the fasting one. This does not mean that bolted flour 
is poisonous, but only that it is a more incomplete 
food than whole wheat. The pigeon which is fed 
whole wheat wiU succumb in the course of time, for 
whole wheat is not a complete food. The pigeon 
which fasts gradually wastes away, but slowly, be- 
cause all the tissues decrease in volume and its physi- 
ological processes slow down. The bird which is fed 
the bolted flour dies earher than the fasted one, be- 
cause the burden of digesting and metaboUzing a 
liberal intake of food requires that his metabolic 
processes go on at a rapid rate. When this demand 
is made upqn it and its diet is so incomplete that 
there can be no repair of its wasted tissues, it wears 
out the more quickly. Such demonstrations do not 
constitute an argument against the use of wheat flour 



THE PLANNING OF THE DIET 141 

as a food. In so far as the latter supplies protein, 
energy and inorganic salts, it is a good food. What 
we should realize is that none of owr vegetable foods 
or the meats are conaplete and ideal foods. Some are 
more deficient than others, and their deficiencies are 
not all alike. Satisfactory nutrition is to be attained 
only through the employment of the right combi- 
nations of foods, and in such proportions as will in- 
sure that the resulting diet will be properly con- 
stituted. We should accept our natural foods for 
what they are, and make proper use of them, rather 
than condemn this or that one because it is lacking 
ia some respect. 

It is fallacious reasoning to attempt to compare 
the money value of certain foods with certain others. 
We may safely compariB the cost of the cereal grains 
or the legumes with each other, or with the tubers 
such as the potato or the sweet potato, or with the 
root foods. It is not possible to compare the cost of 
any of these with milk or the leafy vegetables such 
as cabbage, cauliflower, Swiss chard, collards, 
Brussel sprouts, onions, lettuce, celery tops, spinach, 
turnip tops and other leaves employed as greens. 
Milk and the leafy vegetables are to be regarded as 
protective foods. In some degree eggs are to be con- 
sidered in the same class. Milk and the leafy vege- 
tables should be taken in Uberal amounts. The 
leaves should not be regarded as foods of low value 
because their content of protein, fat and carbohy- 
drate is low, and the content of water high. When 



142 THE NEWER KNOWLEDGE OF NUTRITION 

compared on the basis of chemical composition they 
appear inferior to seeds, but they have a peculiar 
value in their high content of fat-soluble A and of 
mineral elements, which makes them stand in a 
class by themselves among the vegetable food-stuffs. 

No thorough studies of the dietary properties of 
fruits have yet been made, but from their known 
chemical composition and biological functions as 
storage organs, their proper place in the diet can be 
predicted. They are good sources of mineral salts 
and of energy-yielding foods, the sugars. They are 
highly palatable and exert a favorable influence on 
the excretory processes of the kidneys and the in- 
testine. Their liberal use in the diet should be en- 
couraged. 

Owing to the present shortage of certain food- 
stuffs, there has been a tendency to consider the in- 
troduction of certain new products hitherto not 
generally employed in. a large way as human foods, 
and to extend their use by extoUing their virtues. 
Conspicuous among these are the peanut press cake, 
which remains after the oil is extracted by pressure, 
the soy bean and cottonseed flour. The latter prod- 
uct represents a portion of the cottonseed which is 
prepared by first removing the oil, and afterward 
grinding and bolting to obtain a product free from 
hulls and fiber. These movements directed toward 
the utilization of all our food resources are laudable, 
but the information which is disseminated con- 
cerning these products by their enthusiastic pro- 



THE PLANNING OF THE DIET 143 

moters is not in all cases accurate and sufficiently 
complete to serve as a safe guide to the user. They 
are extolled in the time-honored fashion as foods 
rich in protein and energy, but their exact place ia 
the dietary is not sufficiently emphasized. 

There can be no doubt that the peanut is a whole- 
some food, and can be used to advantage in the diet 
of man in moderate amounts. It is likewise a good 
source of protein of fairly good quality. The same 
can be said of the soy bean. The proteins of neither 
of these have extraordinary values. That there are 
no proteins of extraordinary values in the seeds of 
plants yet studied, is apparent from a critical and 
imprejudiced inspection of all of the extensive ex- 
perimental data available. The point to be em- 
phasized in this coimection, is that these are seed prod- 
ucts, and have in a general way the peculiar dietary 
properties common to seeds. Their place in the diet 
is therefore clear. They may be employed in moder- 
ate amoimts along with other seeds and seed prod- 
ucts, provided that they are supplemented with 
sufficient amounts of the protective foods, milk and 
the leafy vegetables. 

With respect to cottonseed products the case is 
somewhat different. The cottonseed has long been 
known to contain something toxic to animals, and ex- 
perience has taught that cottonseed meal, a product 
containing the huUs, cannot be fed hberally to animals 
without disastrous results. Withers and Carruth^ 
have conducted extensive investigations regarding 



144 THE NEWER KNOWLEDGE OF NUTRITION ' 

the nature of the toxic constituent, and have iso- 
lated it as a substance to which the name gossypol 
has been given. It is destroyed by oxidation, and 
by appropriate heat treatment, and some cotton- 
seed products are much less poisonous than others, 
because of the special treatment which they have 
received. The author has fed cottonseed flour to a 
large number of animals, and is convinced that it 
should not be employed in the human dietary in very 
hberal amounts. If the diet is appropriately con- 
stituted with respect to its content of the protective 
foods, cottonseed floiu- which has been thoroughly 
cooked, will, when used in moderation, be found to be 
a useful food-stuff. The data available emphasize the 
need for further careful studies to show how much 
heat treatment is necessary to render cottonseed 
flour harmless. Such knowledge, when available, 
will make possible the standardization of commercial 
products, and will make possible the utilization of 
this vast food resource. 

The paramount importance of maintaining and 
of increasing the production of milk makes it neces- 
sary to utilize a large amount of protein-rich foods in 
the dairy industry. The wisest plan is to extend the 
use of peanut, soy bean and cottonseed products for 
milk production. The cow produces much of her 
milk from coarse feeds, not suitable for human con- 
sumption, but requires liberal protein-rich supple- 
ments in addition. Greater emphasis should be laid 
upon the wisdom of a more liberal purchase of milk 



THE PLANNING OF THE DIET 145 

by the public. This would insure the best utiliza- 
tion of these protein-rich products which have not 
as yet in many quarters found exteiisive use as hu- 
man foods. Experimental data seems to have es- 
tablished that the proteins of the peanut and the soy 
bean are of better quahty than those of the pea or 
the navy bean. From the author's studies of the soy 
bean it appears that its proteins have about the 
same quality as those of the cereal grains, but it con- 
tains three times as much protein as the latter. Its 
content of fat-soluble 4^ is such that a mixture of 
soy bean and starch which has the same protein con- 
tent as the wheat kernel, probably has about the 
same dietary properties as has wheat with respect to 
these two dietary factors. There is no reason why 
the peanut and soy bean should not be employed to 
a greater extent as human foods, but it should be 
kept in mind that good use is already being made of 
these products in the feeding of dairy cows, and that 
if they are withdrawn from this application for use 
as himian foods directly, it will not be easy to find 
something to take their place in the dairy industry. 
Several writers have pointed out that these seeds 
contain the fat-soluble A, and have exhibited growth 
curves which indicate that animals have taken one of 
these seeds properly supplemented so as to correct 
its deficiencies, and have been able to grow to ap- 
proximately the full adult size without the addition 
of more of this dietary essential. The reader is left 
with the impression that the peanut, soy bean and 



146 THE NEWER KNOWLEDGE OF NUTRITION 

cottonseed may serve as an adequate source of fat- 
soluble A. This impression is an unfortunate one, 
for it is certain that even with diets which are com- 
posed largely of these seeds, the content of this sub- 
stance is below the optimum, and in the amounts ia 
which they are likely to enter into the human diet, 
they will never serve as a substitute for the pro- 
tective foods. In the enthusiastic apphcation of the 
biological method for the analysis of food-stuffs, by 
those with Uttle experience, after its description by 
McCoUum and Davis in 1916,^ hasty conclusions 
have been drawn in a number of instances. Mc- 
CoUum and Simmonds have emphasized the necessity 
of observing over long periods, such animals as are 
able to grow at about the normal rate and produce 
a few young and rear them, when confined to ex- 
perimental diets. In many instances it is foimd that 
the interval between litters is too long, or the mor- 
tahty of the young abnormally high, the time neces- 
sary to bring the young to the weaning stage too 
long and the signs of old age appear too early, in 
animals which during the early part of the reproduc- 
tive period appeared to be nearly normal in aU re- 
spects. They have reached the conclusion that it is 
necessary to observe the behavior of the second 
generation when confined to the diet of the parent 
before drawing final conclusions concerning the 
quahty of a diet. In many instances lack of vitality 
is first observed in the inability of the offspring to 
develop normally on a diet which would, in the early 



THE PLANNING OF THE DIET 147 

life of the parent, have been considered entirely sat- 
isfactory. When observations are extended ia this 
way, it becomes apparent that limg infections very 
frequently terminate the lives of the animals, whose 
diets are faulty in some degree, but not so faulty as to 
make their effects strikingly apparent. 

From many questions asked by the pubhc the au- 
thor has gained the conviction that faulty deductions 
have been drawn by others from experimental 
studies, which would lead the inexperienced reader 
to conclude that by the use of any seed products, or 
other food-stuffs of vegetable origin, whose func- 
tions are those of storage organs, that diets can' be 
prepared which are so satisfactory as to make it 
feasible to dispense with a Uberal intake of the food- 
stuffs which we have .designated as protective foods. 
These can be shown to be based upon failiu-e to fully 
appreciate what constitutes a satisfactory demon- 
stration of the adequacy of a diet. Mankind will do 
well to avoid such diets which may, as Golderger 
has suggested, place one in "a 'twiUght' zone within 
which a very sUght change in any of the dietary- 
components may cause an important shift of bal- 
ance." 

McCollum and Simmonds have reported many 
experiments with diets so planned as to be satisfac- 
tory in that all the factors but one afforded a liberal 
margin of safety in offering an abundance over the 
minimal requirements of the animal,^ and the re- 
maining one so adjusted as to represent the actual 



148 THE NEWER KNOWLEDGE OF NUTRITION 

minimum on which the animal can subsist over a 
considerable period. In this way it has been possible 
to demonstrate that the amount of fat-soluble A 
may be reduced to a certain minimum without the 
development of xerophthalmia, whereas the same 
intake of this substance will not prevent the charac- 
teristic eye trouble when the intake of protein is 
likewise sufficiently lowered. They have been able 
to so adjust the components of the diet as to make 
it possible to relieve xerophthalmia either by in- 
creasing the content of protein or of fat-soluble A 
in the food, although it is the lack of the latter which 
is the specific cause of the disease. Such observations 
make it evident that it is impossible to say what is 
the safe minimum of any dietary factor, unless the 
biological values of all the other essential constituents 
of the diet are known. ,This represents an actual 
accomplishment of planning a diet which brings 
the animal into the "twilight" zone, where small 
shifts in the quality of the diet with respect to any 
factor may either distinctly stabilize the metaboHc 
processes of the animal, or may lead to the develop- 
ment of a distinct pathologic state. 

Their studies with the types of diets just described, 
lead them to the conclusion that it is unwise to 
approach very closely the physiological minimum 
with respect to any dietary factor. Liberal consump- 
tion of all of the essential constituents of a normal diet, 
prompt digestion and absorption and prompt evacuation 
of the undigested residue from the intestine before ex- 



THE PLANNING OF THE DIET 149 

tensive absorption of 'products of bacterial decomposition 
of proteins can take place, are the optimum conditions 
for the maintenance of vigor and the characteristics 
of youth. Such a dietary regime can be attained only 
by supplementing the seed products, tubers, roots 
and meat, which must constitute the bulk of the 
diet of man, with the protective foods, milk and the 
leafy vegetables. , 

The results of the study of several representatives 
of eack of the different classes of food-stuffs has led 
the author to the conclusion that, while it is not de- 
sirable to relegate to the backgroimd any of the 
fvmdamental knowledge of food-stuffs which can be 
obtained by chemical methods, and by respiration 
and digestion studies, the fimdamental basis of nutri- 
tion can best be imparted to the pubUc through the 
adoption of a biological classification of the natural 
food-stuffs on the basis of their function. Foods 
other than milk and eggs of both animal and veg- 
etable origin may be arranged into groups according 
to whether they represent principally, fimctioning 
active protoplasm, or deposits of reserve food mate- 
rial, or in animal tissues, highly speciahzed contract- 
ile tissues. From their biological function their 
dietary properties can be fairly accurately predicted. 
This idea, together with the knowledge that milk, 
eggs and the leafy vegetables, the protective foods, 
are so constituted as to correct the dietary deficiencies 
of the seeds, tubers, roots and meat, shovild form 
the central idea in the teaching of the science of 



150 THE NEWER KNOWLEDGE OF NUTRITION 

nutrition. It should be emphasized that the diet is 
a relatively complex thing, and that none of the 
essential constituents can be ignored in its planning, 
but that the observance of certain general rules of 
procedure will insure that any faults in the diet 
will be reduced to a minimum. 

It is of special moment at this time to emphasize 
the importance of the dairy industry ia its relation 
to the pubUc health. Mankind may be roughly 
classified into two groups. Both of these have de- 
rived the greater part of their food supply from 
seeds, tubers, roots and meat, but have differed in 
respect to the character of the remainder of their 
diets. One group, represented by the Chiaese, 
Japanese and the peoples of the Tropics generally, 
have employed the leaves of plants as almost their 
sole protective food. They likewise eat eggs and 
these serve to correct their diet. The other group 
includes the peoples of Europe and North America 
and a few others. These have hkewise made use 
of the leaves of plants, but in lesser degree, and have, 
in addition, derived a very considerable part of then- 
food supply from milk and its productfe. 

Those peoples who have employed the leaf of the 
plant as their sole protective food are characterized 
by small stature, relatively short span of life, high 
infant mortaUty, and by contended adherence to the 
employment of the simple mechanical inventions of 
their forefathers. The peoples who have made Ub- 
eral use of milk as a food, have, in contrast, attained 



THE PLANNING OF THE DIET 151 

greater size, greater longevity, and have been much 
more successful in the rearing of their yoimg. They 
have been more aggressive than the non-milk using 
peoples, and have achieved much greater advance- 
ment in Uterature, science and art. They have 
developed in a higher degree educational and polit- 
ical systems which offer the greatest opportunity 
for the individual to develop his powers. Such 
development has a physiological basis, and there 
seems every reason to beUeve that it is fundamentally 
related to nutrition. 

In the United States, we have in the past de- 
rived no less than 15 to 20 per cent of our total 
food supply from the products of the dairy. The 
iavestigations of recent years have thrown a new 
Ught on the importance of this increment of our diet. 
It has become evident that milk is the greatest 
factor of safety ia our nutrition, and it is certain 
that we could not have accompHshed what we have, 
had we dispensed with milk as a food. 

The situation of the dairy industry is at the present 
time precarious. The cost of feeding-stuffs and of 
labor have enormously increased during the last 
few years, and consequently the cost of milk produc- 
tion. Advance in the cost of milk to the consumer 
has been made unavoidable. Every advance in the 
price has, however, met with great resistance by the 
pubUc, and with each rise there has been a distinct 
drop in the amount purchased. The milk dehvered 
in the city of Chicago has fallen off from about a 



152 THE NEWER KNOWLEDGE OF NUTRITION 

million and a quarter quarts daily to about seven 
hundred thousand quarts, within a year. Similar 
reductions in sales have occurred almost everywhere 
in the Eastern half of the country, solely because of 
the rise in price. This has resulted in the discourage- 
ment of producers everywhere, and in a movement 
toward the reduction of the number of dairy cows. 

There can be no doubt that there is great lack of 
knowledge by the people generally as to the impor- 
tance of milk and other dairy products in the diet. 
There is no substitute for milk, and its use should 
be distinctly increased instead of diminished, re- 
gardless of cost. Every possible means should be 
employed to reduce the cost of distribution. The 
necessity for the liberal use of milk and its products 
both in the diets of children and adults should be 
emphasized in order to stem the ebbing tide of its 
production. It has been pointed out that the value 
of milk as a food cannot be estimated on the basis 
of its content of protein and energy. Even when 
measured by this standard it compares most favor- 
ably with other foods, but it has a value as a protect- 
ive food, in improving, the quality of the diet, which 
can be estimated only in terms of health and eflSl- 
ciency. 

An examination of any large groups of people in 
the cities, will show that where there is a high mor- 
taUty from tuberculosis, milk is not being used to 
any great extent, and in any large group where 
milk purchases are large this disease is not a menace. 



THE PLANNING OF THE DIET 153 

It is well known that in institutions where tuber- 
culosis is successfully treated milk forms the prin- 
cipal article of the diet of the inmates. This has 
resulted from clinical experience. There is no other 
effective treatment for this disease than that of 
providing fresh air, insisting upon rest and of height- 
ening the body's powers of resistance through the 
Uberal use of milk for the correction of faults which 
the diet wiU inevitably have when it consists too 
largely of seed products, tubers, roots and meats. 
Tlie importance of diets of this character in the 
etiology of tuberculosis, has not hitherto been 
appreciated. In the hght of facts presented in the 
previous chapters of this book, there can be no 
reasonable doubt that the importance of poor 
hygienic conditions and of poor ventilation have 
been greatly over-estimated, and that of poor diet 
not at all adequately appreciated as factors in pro- 
moting the spread of this disease. Milk is just as 
necessary in the diet of the adult as in that of the 
growing child. Any diet which wUl not support 
normal development in the yoimg will not support 
optimum well-being in the adult. Milk is our greatest 
protective food, and its use must be increased. The 
price must be allowed to go up, so long as the cost 
of production makes it necessary, and up so far as is 
essential to make milk production a profitable busi- 
ness. Unless this is done, the effects will soon be- 
come apparent in a lowering of otir standards of 
health and efficiency. 



INTRODUCTION TO THE LEGENDS TO THE 
CHAETS 

The data upon which the foregoing discussion of 
diet is based, consists of about three thousand feeding 
experiments. Most of these were carried out with 
domestic rats, but in order to demonstrate the gen-' 
eral applicability of the results of tests made on one 
species to other species of animals, numerous feeding 
tests were made on farm pigs, cattle, chickens, 
guinea pigs and a few on pigeons. These all indicate 
that the chemical requirements of these different 
types of animals are essentially the same. The 
following charts present the growth curves of rats, 
fed a series of diets which illustrate the type of re- 
sults from which the conclusions in this book are 
drawn. In each case the curve is the actual record 
of an individual which fairly represents the behavior 
of from four to six or more animals. 

The broken curve marked N with the sex sign 
(d'= male; 9 = female) represents the normal ex- 
pectation of growth in each sex when fed a mixed 
diet containing several seeds and a liberal supply 
of milk. Vertically the curves designate body weight ; 
horizontally from left to right the charts record 
diu-ation of experiment, each square representing 

154 



LEGENDS TO THE CHARTS 155 

four weeks. A break in a curve marked Y, indicates 
the birth of a Utter of young. 

Although experiments are described only for the 
wheat, rice and oat kernel among the seeds, similar 
records are available for all the more important 
seeds used as foods in America, and these warrant 
the statement that seeds as a class closely resemble 
each other in their dietary properties. A close re- 
semblance likewise exists among the several leaves 
which have been studied, so that the edible leaves 
may be regarded as having in a general way the same 
dietary properties. 

Chakt 1. — ^Lot 417 shows the results of restricting young rats to 
a diet of purified protein, salts, carbohydrate and agar-agar, together 
with an extract of a natural food-stuff which furnishes the dietary 
factor, water-soluble B, the substance which prevents beri-beri. 
The diet was complete except for the absence of the fat^oluble A. 
As a rule there develops in animals so fed, a type of xerophthalmia, 
which is due to the lack of the fat-soluble A. When a fat or other 
natural food which is rich in cellular structures (as contrasted with 
reserve food materials), is added to a food mixture of this type, the 
resulting diet becomes capable of inducing growth. 

Lot 418, Period 1, shows the curves of body weight of rats fed a diet 
similar to that described above for Lot 417, but differing in that it 
contained butter fat (fat-soluble A) but lacked the extract of natural 
foods, and, therefore, contained no water-soluble B. On this diet 
xerophthalmia does not develop, but the animals ultimately lose 
muscular control and manifest symptoms suggestive of beri-beri in 
man. Growth is not possible on this diet, but everything which is 
needed in the diet so far as chemical analysis could show, is present. 

These results show the necessity of a biological analysis of food- 
stuffs. Growth at once took place when, in Period 2, the dietary 
essential water-soluble B, which is likewi& soluble in alcohol, was 
added to the diet. This dietary factor is abundant in all natural 



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LEGENDS TO THE CHARTS 157 

foods. In investigations of the nature of those here described, it is 
usually added as an alcoholic extract of a natural food. 

Lot 419 shows the type of growth curves secured with diets con- 
taining both fat-soluble A and water-soluble B, in addition to the 
long recognized food substances, protein, carbohydrate, fat and a 
satisfactory supply of the inorganic elements essential for the nutri- 
tion of an animal. There is much reason to believe that each of the 
two unidentified dietary factors A and B contains but a single chem- 
ical complex which is physiologically indispensable, and not a group 
of such substances. 

Chart 2. — This chart illustrates the nature of the dietary defi- 
ciences of the cereal grains, as revealed by feeding a single variety 
of seed with the addition of certain purified food substances. Wheat 
is a typical representative of the group of seeds. 

The wheat kernel when fed as the sole source of nutriment, or when 
supplemented with protein alone or with fat-solubie A alone (in 
butter fat), does not induce any growth in a young animal. Wheat 
supplemented with the three inorganic elements, calcium, sodium 
and chlorine, and with no other additions, induces slow growth for 
a time. In other words, the salt content is the first limiting factor 
in seeds from the dietary standpoint. These facts are not illustrated 
by growth curves. 

Lot 223 illustrates the growth of young rats when fed wheat to- 
gether with two purified food additions, viz., protein and a salt 
mixture of suitable composition. The dextrioized starch in this diet 
has no special significance. On this diet animals may grow to nearly 
the fuU adult size at the normal rate, and in some cases a small htiter 
of young may be produced. The young as a rule will be allowed to 
die within a few days. On such a diet xerophthalmia will ultimately 
develop, and this forms the terminal event in the Uves of the animals. 
This shows that the content of fat^oluble A in wheat is below the 
amount required to maintain an animal in a state of health over a 
long period. This fact is further illustrated by the record of rat 
223-B, whose diet was Uke that of 223, except that the former con- 
tained 5 per cent of butter fat. Butter fat is the best known source 
of fat-soluble A. 

Lot 380, Period 1, shows how slowly growth proceeds when the 
diet consists of wheat, supplemented with two purified food addi- 
tions, protein and fat-soluble A (as butter fat). The deficiency of 



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LEGENDS TO THE CHARTS 159 

the wheat kernel in certain inorganic elements is illustrated by the 
great acceleration of growth in Period 2, when a suitably constituted 
salt mixture was added to the diet of Period 1. 

Lot 319 shows the slow growth of a rat when fed wheat supple- 
mented only with the requisite inorganic salts and fat-soluble A. 
The proteins of the wheat kernel are not of very good quality, and 
must be enhanced by further protein additions before growth can be 
normal. 

Lot 223-B illustrates the fact that the optimum rate of growth is 
secured with wheat supplemented with three purified food addi- 
tions, viz., salts, fat-soluble A and protein. When wheat is improved 
with respect to these three dietary factors, it becomes a complete 
food, and supports the production of the normal number of young, 
and the young are successfully reared. What is true of wheat is 
likewise true in a general way of the other seeds. Seeds are similar 
in their dietary properties. In other words, the mineral content of 
any seed must be improved by suitable salt additions, its protein 
content must be enhanced by the addition of other proteins which 
yield in greater abundance those amino-acids which it yields in small 
)amounts, and in most cases additional fat-soluble A must be added 
in order to prevent the ultimate develppment of a pathological con- 
dition of the eyes. A liberal supply of milk will correct aU the defi- 
ciencies of a seed diet. 

Chart 3. — ^In the process of polishing, both the germ and the bran 
layer of the rice kernel are rubbed off, thus removing the cellular 
structures and leaving only the endosperm. This consists almost 
entirely of proteins, starch, a small amount of fats, and of mineral 
elements in the form of salts. Its proteins are of relatively low value 
for inducing growth. Polished rice is, therefore, practically com- 
parable, from the dietary standpoint, to the diet of purified food- 
stuffs described in Chart 1. 

Lot 317 shows the behavior of young rats which were fed polished 
rice supplemented with two dietary factors, viz., a suitable salt 
mixture and fat-soluble A. This does not support growth, since the 
diet is still deficient in two respects. It lacks the second dietary 
essential, water-soluble B, and its proteins are of too poor quality 
for the support of growth in the amoimt suppUed by 90 per cent of 
rice. Such a diet as that of Lot 317 will permit the development 
of a condition in rats similar to beri-beri in man. 



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LEGENDS TO THE CHARTS 161 

Lot 324 shows the effects on young rats of feeding them on a 
mixture consisting of polished rice supplemented with purified pro- 
tein, a suitable salt mixture and fat-soluble A. The polished rice 
evidently contains some cellular elements and, therefore, some of the 
water-soluble B, for the animals were, able to grow very slowly in 
some cases, and to remain aUve during several months. Lot 401 
illustrates the remarkable effects of adding to this diet an alcohoUc 
extract of wheat germ. This extract fmnished a liberal amount of 
water-soluble B (hkewise soluble in alcohol) and renders the diet 
complete. The alcohol was employed to dissolve this dietary essen- 
tial from the germ, and was evaporated completely before the ration 
was fed. 

Lot 383 shows the dietary properties of impolished as contrasted 
with polished rice. The former which contains the cellular struc- 
tures of the germ and the bran layer, is rendered complete as a food 
by the addition of protein, fat-soluble A and salts. Young rats do 
not grow at all when fed solely upon unpolished rice, without these 
additions. Unpolished rice closely resembles wheat, com, rye, 
barley and other seeds in its dietary properties. 

Lot 401 shows the behavior of young animals when fed polished 
rice supplemented in four respects, viz., protein, a suitable salt 
mixture, fat-soluble A and water-soluble B. On this diet, young rats 
grew to the normal adult size, reproduced repeatedly and were able 
to rear a few of their young. The omission of any one of these addi- 
tions would lead to almost complete failure of young animals to 
develop on this diet. 

These examples make clear the method of procedure in making a 
biological analysis of a food-stuff. The latter consists of a suitably 
planned series of feeding experiments in which single and multiple 
purified food additions are made to a single natural food-stuff, and 
observations are made as to the abiUty of young animals to grow 
and perform the functions of adult life on the resulting food mixtiu'es. 
In this way information can be secured which chemical methods 
are imable to reveal. 

Chakt 4. — ^These records illustrate the biological analysis of the 
dietary properties of the oat kernel (rolled oats). Lots 623 and 654 
show the failure of young rats to grow on rolled oats supplemented 
with either a suitable inorganic mixture, or with purified protein 
as the only addition. Correction of these factors is necessary, but 



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LEGENDS TO THE CHARTS 163 

there are still other faults in the oat kernel which must be corrected 
before it becomes a complete food. This is illustrated by the re- 
maining records in this chart. 

Lot 625 shows that when the oat kernel is supplemented with 
both a suitable salt mixture and fat-soluble A, it can support growth 
at a good rate for three months, but does not permit the animal to 
reach fuU adult size, and leads to early failure. The protein of the 
oat kernel has a sUghtly higher value for growth than has that of 
either wheat or corn, but the amount furnished by 90 per cent of 
rolled oats is below the optimimi for the support of growth in a 
rapidly growing species. A diet rich in rolled oats produces very 
hard, pasty feces, which are difficult of elimination. This appears 
to be a factor of importance in preventing the normal development 
of the experimental animals in this series. 

Lot 624 further illustrates the inadequacy of rolled oats sup- 
plemented with both a suitable salt mixture and protein (casein). 
This food mixture lacks a sufficient amotuit of fat-soluble A, and 
unless there is an addition of this substance, the animals always 
develop the eye trouble (xerophthalmia) described on page 87. 

Lot 655, shows the growth curve of an animal fed rolled oats 
supplemented with protein, an appropriate mineral salt mixture and 
fat^oluble A. In this case the protein employed was Casein of nulk. 
This ration is dietetioaUy complete, so far as its chemical composition 
is involved, but it did not support normal development to the fiill 
adult size. It is not possible to state just how far the stunting was 
due to the pasty character of the feces formed from this diet, and 
how far the results should be attributed to the failure of casein to 
supplement the amino-acid deficiencies of the oat proteins. Much 
better nutrition is secured with this diet when the casein is replaced 
by another protein, gelatin, as is shown by the records of Lot 647. 

Lot 647 illustrates the completeness of a diet derived from rolled 
oats supplemented with an appropriate salt mixture, fat-soluble A 
and the protein, gelatin. When Charts 2, 3 and 4 are compared, 
they show the striking similarity from the dietary standpoint of the 
three seeds, wheat, rice (unpolished) and oat kernels. 

It is not to be concluded from these experiments which show the 
faulty character of these seeds as foods, that they are imdesirable 
constituents of the diet. Neither is it necessary or practicable to 
supplement in practice the seeds which we eat with additions of 



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LEGENDS TO THE CHARTS 165' 

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protein, salts, etc., in the maimer employed in the biological analysis 
of these which we have described. There are two classes of j/rotedive 
foods, milk and the leafy vegetables, which when taken along with 
the seeds and their products, make good their deficiencies, and render 
Jhe diet complete. These correct the inorganic deficiencies (caldum, 
sodium and chlorine), insure a sufficient amourd of fat-solvble A, and 
enhance the value of the proteins of the seed, 

Chabt 5. — Each of the more important seeds which are employed 
in human and animal nutrition, have been studied by the methods 
employed for wheat, rice and the oat kernel, and the results show 
that the seeds aU resemble each other in a general way in their dietary 
properties. They all require the same kinds of supplementaiy addi- 
tions to make them complete foods. It would be expected, therefore, 
that mixtures of any seeds should not form complete diets. The 
following experiments demonstrate that this is indeed the case. 

Lot 722 shows the failure of animals to grow when confined to a 
mixture of corn and flaxseed oil meal. After nearly four months of 
stunting there was an immediate response with growth when the 
inorganic content of the diet was supplemented with a suitable salt 
mixture. 

Mixtures of seeds will, in nearly all cases, furnish proteins in 
greater value than those of the individual seeds fed singly, since the 
amino'acids in which they are relatively deficient are not the same 
in different seeds. The seeds all contain some of the fat-soluble A, 
but not as much as is desirable in the diet. In seed mixtures there 
is only a relative shortage of this dietary essential. The deficiency 
of certain inorganic elements is, therefore, the first limiting factor 
in mixtures of seeds as food-stuffs. In many of the growth curves 
exhibited in the charts, complex salt mixtures were added, since at 
the time the experiments were carried out, our knowledge concerning 
the inorganic factor was still very incomplete. It is now known that 
but three elements need be added to seed mixtures, viz., calcium, 
sodium and chlorine. 

Lot 713 shows the failure of five seeds to support growth. In 
Period 2, the correction of the inorganic deficiencies of the diet was 
followed by a prompt response with growth. The poor quality of the 
proteins and relative shortage of fat-soluble A, will in time lower the 
vitaUty of animals fed such a seed mixture, when only the inorganic 
factor is corrected. 






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LEGENDS TO THE CHARTS 167 

Lot 959 shows that the addition of fat-soluble A (as butter fat) 
to a mixture of three seeds, wheat, com and oats, does not produce 
a food which can support growth except at a very slow rate. In 
Period 2, the correction of the inorganic deficiencies of the diet was 
followed by a prompt response with growth. 

Lot 1012, in Period 1, received three seeds supplemented with 
both protein (casein) and fat-soluble A, but could not grow on this 
diet. In Period 2, the addition of the necessary salts produced an 
immediate response with growth. 

Lot 714-B, 'which were fed three seeds, suffered complete suspen- 
sion of growth. There was no response in Period 2, to the addition 
of fat-soluble A in butter fat. Although both protein and fat- 
soluble A are desirable additions to any seed diet, and are necessary 
before the optimiun nutrition can be attained, the inorganic defi- 
ciencies must be corrected before any noticeable benefit can be de- 
rived from the correction of the other factors. (Compare 959-714-B.) 

Chart 6. — In marked contrast to the failure of young animals to 
grow on a diet restricted to seeds, one can secure very satisfactory 
rations from mixtures of leaf and seed. The leaf is a cell rich struc- 
ture; the seed, a cell poor storage organ. With this difference in 
function go corresponding differences in dietary properties. (See 
pages 43-44.) 

These curves illustrate the relative values for the support of growth 
and reproduction of diets derived from alfalfa leaf flour 40 per cent, 
and a seed 60 per cent. It wUl be seen that these corresponding leaf 
and seed mixtures are not of equal value. In a general way the leaves 
all resemble each other in their dietary properties, and form a dis- 
tinct group of food-stuffs as do the seeds. 

Lot 685 shows the possibihty of securing a normal growth curve 
and repeated reproduction with a rat restricted to a mixture of alfalfa 
leaf flour 40 per cent and rolled oats 60 per cent. Of the six Utters 
(33 young) borne by mothers which had grown up on this diet, 16 
young or 50 per cent were successfully reared to weaning time. 
Despite the fact that an animal can grow at a rate which we may 
regard as normal on this food mixture, it is not of a highly satisfactory 
character. Rolled oats and alfalfa leaf make a better diet than the 
alfalfa leaf with any other seed which we have studied. It is inter- 
esting that these proportions between alfalfa leaf and rolled oats give 
better results in the nutrition of the rat than any others. 






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LEGENDS TO THE CHARTS 169 

Lots 6S7 and 686, show that there is little difference in the values 
of mixtures of the alfalfa leaf with the wheat kernel as compared 
with the com kernel. Both, in the proportions here employed, fail 
to induce growth at the "normal" rate, and the number of young 
produced was approximately one-fifth that which a female rat will 
produce when her diet is of excellent quaUty. A well-nourished 
female rat may be expected to produce five litters of young. 

Lot 478 shows that even with a simple mixture of alfalfa leaf 
flour 40 per cent and polished rice 60 per cent, rats were able to grow 
to about 83 per cent of the normal adult size and to produce young. 
The rat whose curve is shown had two litters. All young from 
mothers which had grown up on this diet were allowed to die dming 
the first few days after birth. 

Lots 688 and 717, show that combinations of peas or of cottonseed 
with the alfalfa leaf flour form food mixtiu'es which can support 
growth at a slow rate, but are inferior to certain other combinations 
of leaf and seed. 

There are very great possibihties for improving our practices in 
the utilization of feeding-stufis in animal production. We need 
exact knowledge regarding the best combinations and proportions 
in which to feed our natural products. 

Chakt 7. — It is easily possible to prepare diets which are derived 
solely from vegetable som-ces, which will induce growth from weaning 
time to full adult size and support the production of young. Success 
in this direction involves the emplojmient of suitable combinations 
of leaves, together with foods of plant origin whose functions are 
those of storage organs, viz. : seeds, tubers, and roots. The records 
here presented show the most successful results whibh we have ob- 
tained with mixtures of leaf and seeds. 

Lot 273 shows the results of restricting young rats from weaning 
time to a diet derived entirely from the alfalfa leaf flour, com and 
peas. The peas were cooked at 15 pounds pressure for one hour in an 
autoclave. The other constituents of the diet were fed raw. 

The female rat marked. First Generation, never grew to the full 
adult size, but others in the same cage with her did. The curve of 
this particular rat is presented because she became the great grand- 
mother of a litter whose ascendants for four generations ate, beyond 
the weaning age, nothing but this monotonous mixture of vegetable 
foods. 



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LEGENDS TO THE CHARTS 171 

This ration did not induce optimum nutrition. The number of 
yovmg produced was approximately half what well-fed rats normally 
produce, and the mortality of the young was high. Although the 
breeding records were poor and the litters small, most of these young 
were reared. Notwithstanding this, the vigor of the fourth genera^ 
tion appeared to be as great as that of the first. 

The above mixture gives better results in the nutrition of the rat 
than any other proportions in which these three food-stuffs can be 
combined. If the amount of alfalfa leaf is raised to 40 per cent or 
reduced to 20 per cent, and the content of corn is reduced or increased 
respectively, few young will be reared. The importance of knowing 
the exact proportions in which to combine our natural food-stuffs 
in order to secure the optimum results in nutrition, especially in 
animal production, will be evident from these results. 
. Chart 8. — ^This chart affords an illustration of the great differences 
in the degree in which a supplementary addition of protein may en- 
hance the value of the proteins of a natural food-stuff. The curves 
should be considered in pairs. 

Lot 493 shows the results of feeding a diet deriving its protein 
content entirely from the wheat kernel. The diet contained but 7 
per cent of protein, an amotmt too small because of the relatively 
poor quality of the wheat proteins, to support growth at the optimum 
rate. The group of rats which were fed this diet grew at about half 
the normal rate. 

Lot 652 received the same diet, with 10 per cent of the carbo- 
hydrate replaced by the protein gelatin. The latter is one of the 
"incomplete" proteins, since it lacks three of the amino-acids which 
are essential for the" nutrition of an animal. A diet which contains 
gelatin as its sole protein, no matter how much gelatin it may con- 
tain, cannot induce any growth whatever in a young aoimal. Lot 
652, however, grew at the optimum rate. This result shows that the 
added gelatin made good a limited supply of certain amino-acids in 
the wheat proteins of the diet. This formed the limiting factor in 
determining the slow rate of growth in Lot 493. Gelatin is shown by 
this experiment to supplement well the proteins of the wheat kernel. 

Lots 756 and 785, show the stunting of young rats fed diets which 
derived their protein entirely from a mixture of peas and gelatin, 
and a mixture of navy beans and gelatin respectively. Both diets 
contained about 18 per cent of protein. When of good quality this 



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LEGENDS TO THE CHARTS 173 

amount suffices for the support of normal growth. Combinatioiis 
of pea proteins with gelatin, and of bean proteins with gelatin, yield 
amino-acid mixtures which are deficient in some way. 

In Period 2 in both cases, the diets differed from those of Period 1, 
only in that the gelatin was replaced by an equal amount of casein 
from milk. This change led to great improvement in the quality of 
the protein in the diets, and growth at once proceeded at a good rate. 
Gelatin does not greatly enhance the value of the proteins of either 
the pea or the bean, whereas casein does. 

Lots 646 and 647 show the effect on growth, of feeding a diet con- 
taining but 9 per cent of protein derived solely- from rolled oats 
(Lot 646), and the same diet with 10 per cent of carbohydrate re-' 
placed by gelatin. In the former case, growth was early suspended, 
but in the latter, growth proceeded at the optimum rate to full 
maturity. This result shows that gelatin supplements the proteins 
of the oat kernel in a very satisfactory manner. (See discussion 
under Lots 493 and 652.) 

Lots 649 and 651, show the growth curves of rats fed, in the former 
case a diet which derived its protein content of about 7 per cent 
entirely from the com kernel, and in the latter case the same diet 
with 10 per cent of its carbohydrate replaced by gelatin. In marked 
contrast to the effects of feeding gelatin together with wheat or oat 
proteins, there is no improvement in the quality of corn proteins 
through combining these with gelatin. Gelatin does not supplement 
the peculiar amino-acid deficiencies of the corn kernel. 

Chart 9. — ^The records in this chart give an idea of the values of 
the proteins derived from mixtures of two seeds. Each of the diets 
described contained 9 per cent of protein. It has been established 
that this content of protein in a ration, when it is derived from either 
the wheat, corn or rice kernel alone, does not support growth at a 
rate much faster than half the normal rate. We, therefore, fed a 
series of diets in which the protein content was adjusted at this level, 
and derived from combinations of two seeds, in order to find the 
most fortunate combinations of seeds as sources of proteins for 
growth. Normal growth is secured on diets of this character, only 
in those cases where the proteins of one seed enhance those of the 
other seed present in the diet. We have not been able to find any 
two seeds whose proteins, when fed together even approximate the 
value of the proteins of milk. 



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LEGENDS TO THE CHARTS 175 

Lot 1366, derived 3 per cent of protein from millet seed and 6 per 
cent from the soy bean. The deficiencies of the diet, aside from the 
character of the proteins, were all made good by suitable additions 
of salts and butter fat. On this diet the growth was slow, and the 
animals remained tmdersized. On this diet three females have pro- 
duced four litters (23) young of which but three individuals were 
weaned, the others being allowed to die in infancy. This protein 
mixture is of relatively low biological value. 

Lot 1339 derived 6 per cent of protein from rolled oat^and 3 per 
cent from flaxseed oil meal. Two females grew up on this diet. 
One remained sterile, and the other produced but one litter of 
young (7). These were finally weaned after a long period of infancy 
in which their growth was very slow. They were very small and 
runty when weaned. A protein mixture derived from these two 
seeds is of relatively poor quality. 

Lot 1338 derived 6 per cent of protein from the wheat kernel and 
3 per cent from flaxseed oil meal. Growth was below the normal 
rate, and two females have produced but three litters (18) young. 
But five of these were successfully weaned. Proteins derived from 
these two seeds are of relatively low biological value. They sufficed 
for the s.upport of a fair rate of growth, but not for the additional 
strain of reproduction. This mixture must have both protein and 
fat-soluble A additions in order to produce the optimum results in 
nutrition. 

Chart 10. — ^Like the preceding chart, this shows the relative 
biological values of the protein mixtures derived from mixtures of 
two seeds. The diet was made adequate in every respect, except 
the protein, which was in all cases adjusted so as to form 9 per cent 
of the food mixture. The reason for this has been made clear in the 
discussion of Chart 9. 

Lot 1350 derived 6 per cent of protein from rye, and 3 per cent 
from flaxseed oil meal. Growth fell slightly below the normal 
expectation. One female and her daughter have produced five litters 
(30) young, of which but five individuals have been reared. This 
diet is not quite satisfactory as is shown by the reproduction records, 
and because of the poor quality of its proteins, and shortage of fat- 
soluble A. 

Lot 1375 secured 6 per cent of protein from rye and 3 per cent 
from millet seed. One female which grew up on this diet has had 



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LEGENDS TO THE CHARTS 177 

two litters of young, all of which were allowed to die in infancy. 
Another female remained sterile. It is evident that this combination 
of proteins does not form a fortunate mixture. 

Lot 1378 derived 6 per cent of protein from peas and 3 per cent 
from miUet seed. Growth on this diet was slower than the normal 
expectation, and reproduction was below normal. Two females 
produced four litters (17) of young, of which but nine individuals 
were finally weaned at an advanced age. These were very small for 
their age. Combinations of pea and millet seed proteins do not 
appear to have a very high biological value. 

These histories selected from a long series of similar experiments 
in our records make it clear that it is not easy to find mixtures of 
two seeds whose proteins are of such a character as to supplement 
each other's deficiencies, in the yields of certain amino-acids, and 
produce mixtures of high biological value for growth and the promo- 
tion of physiological well-being. In order to demonstrate the effects 
of a limited protein content, or of proteins of poor quality in the diet, 
experiments must be continued over a relatively long period of time. 
Observations of man or animals on such diets may lead to faulty 
deductions when the experiments are of short duration. 

Chabt 11. — This chart illustrates in a general way the content of 
the two unidentified dietary essentials, fat-soluble A and water- 
soluble B, in certain natural foods. The diet in all cases consisted 
principally of purified food substances, and was adequate for the 
support of growth, except that its content of fat-soluble A and 
water-soluble B was derived from the small addition of natural food. 
As win appear from the records ia Chart 12, these additions of natural 
food-stuffs, probably furbished a sufScient amount of water-soluble 
B to support normal growth, so it may fairly be said that these 
records afford more nearly an estimation of the content of fat-soluble 
A in each of the natural foods employed. 

Lot 723 shows that 20 per cent of flaxseed does not supply enough 
of the fat-scduble A to support normal growth in a young rat. 

Lot 716, shows that 25 per cent of miUet seed supplied enough of 
both the unidentified dietary essentials for the support of nearly 
normal growth, aad induced sufSciently good nutrition to make 
possible the production of nearly the normal number of young. 
The female rat usually produces five litters of young before she 
reaches the age of fourteen months, which age marks the end of her 




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LEGENDS TO THE CHARTS 179 

period of fertility. The rat whose curve is shown, had four litters 
during the first thirteen months of her life. The first two litters died 
early, but the third and fourth, which were bom after butter fat 
(more fat^oluble A) was added to the mother's diet, were success- 
fully brought to weaning age. 

Lot 633, whose diet derived both the unidentified dietary essentials 
from its content of 20 per cent of alfalfa leaf, remained distinctly 
imdeisized, and produced but two litters of young, all of which died 
in early infancy. 

Lot 632, which received but 10 per cent of alfalfa as its sole source 
of fat-soluble A and water-soluble B, grew slowly, and never reached 
a body weight greater than half the normal adult size, and produced 
no young. 

Lot 631 was unable to grow at all when restricted to 5 per cent 
of alfalfa leaf as its sole source of both the unidentified dietary 
essentials, but responded at once with growth when the content of 
leaf was raised to 30 per cent. 

Lot 710 failed to grow well when restricted to a diet which derived 
its fat-soluble A and water-soluble B from 15 per cent of hemp seed. 
The oil seeds, judging from the limited data available, seem to con- 
tain more of the fa^soluble A than do the cereal grains, but less than 
millet seed. The latter is richer in this substance than any other 
seed yet studied. 

Chart 12. — ^These records were obtained with diets which derived 
their content of water-soluble B entirely from the amount of natural 
food-stuff which each contained. The basal diet consisted of purified 
protein, carbohydrate, a suitable mineral salt mixture, and butter 
fat to furnish the fat-soluble A. The curves give an approximate 
idea of the minimum amount of each of several natural food-stuffs 
which are necessary to furnish sufficient water-soluble B to enable a 
young rat to grow and reproduce. 

Lots 645, 475 and 676 demonstrate the relative richness of the 
wheat kernel in water-soluble B. Even 15 per cent furnishes enough 
to enable a young rat to grow to approximately the full adult size, 
and to produce several litters of young. None can be successfully 
weaned on this diet. Even with 25 per cent of jffheat in the diet, 
we have not seen a Utter of young brought to the weaning age when 
the mother was restricted to this type of diet. When the wheat is 
increased to 35 per cent of the food mixture some young can be 



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LEGENDS TO THE CHARTS 181 

reared, but the mortality is still very high. With higher levels of 
wheat substituted for carbohydrate in this formula, the successful 
rearing of young becomes the rule. 

Lot 695 shows that 25 per cent of cooked peas in the diet as the 
sole source of water-soluble B furnishes a su£Scient amount of this 
substance to enable young rats to grow well and produce young. 
None were reared by any of the female rats in this lot. The peas 
were soaked in water and heated for an hour and a quarter in an 
autoclave at fifteen pounds pressure, dried and ground. This treat- 
ment is approximately the equivalent of the heat employed in the 
processing of canned fruits and vegetables. There seems to be Uttle 
loss of water-soluble B as the result of such heating. 

Lot 696 shows that 25 per cent of navy beans, which had been 
soaked and heated in a manner similar to that described for peas 
(Lot 695), supplied enough of water-soluble B to enable rats to grow 
to full adult size and reproduce. Eight yoxmg out of eighteen young 
(2 litters) were reared by mothers confined to this diet. 

Chabt 13. — ^It has been pointed out (page 46) that the tuber 
and the edible root are both storage organs, and, therefore, poor in 
cellular structures, and that their dietary properties are very closely 
similar to the seeds. The records of young rats which were fed mix- 
tiues of potato and peas, supplemented in various ways according 
to the biological, method of food analysis, demonstrates the truth 
of this assertion. 

Lot 1405 illustrates the slow growth and early death of a rat fed 
a mixture of peas and potato, supplemented with the mineral el- 
ements, calcium, sodium and chlorine. An inspection of the remain- 
ing curves in the chart reveals the fact that the diet is still deficient 
with respect to fat-soluble A, and in no other respect. 

Lot 1450, Period 1, shows the failure of animals to grow when fed 
peas, potato and fat-soluble A. When in Period 2, pure sodium 
chloride (common salt) and calcium carbonate (chalk) were added, 
growth became possible at the normal rate. Two Utters of young 
have been born and all were successfully weaned. This result in- 
dicates that the protein content derived from peas and potato is 
of satisfactory character, and this conclusion is supported by the 
records of Lot 1414, which -has been successful in growth and repro- 
duction when restricted to this protein mixture. To this mixture of 
peas and potato, both the inorganic content and the content of fat- 






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LEGENDS TO THE CHARTS 183 

soluble A must be modified by suitable additions in order to make it 
dietetically complete. ' 

Lot 1423, Period 1, shows failure of animals to ^ow on a diet of 
peas and potato supplemented with purified protein. In Period 2, 
fat-soluble A was added, but still growth could not take place. Li 
Period 3, the addition of calcium, sodium and chlorine, rendered the 
diet complete. Two females have produced three litters (24) young, 
of which 16 have been successfully weaned, and the remaining ones 
are apparently normal, but tmder weaning age. 

Lot 1414 shows that good growth and reproduction are possible 
on a diet derived from peas and potato, supplemented with the 
necessary salts and fat-soluble A, and gives an idea of the quality of 
the protein mixture derived from these som-ces. It is of interest to 
note that the proteins of the pea when taken in the amount f tmiished 
by this diet (about 18 per cent) and forming the sole proteins of the 
diet, do not support normal growth even when the diet is made com- 
plete with respect to all other factors. The proteins of the potato 
are of such a nature as to enhance the value of the proteins of the 
pea. 

In preparing these food materials the potatoes were steamed, 
skinned, dried and ground. The peas were soaked, heated in an 
autoclave at fifteen pounds pressure for an hour and a half, dried 
and ground. The ingredients of the diet were ground so as to make 
it impossible for the rats to pick out and eat them separately. 

Chaet 14. — These records illustrate the dietary properties of a 
mixture of the com kernel and potato. Like the preceding chart 
they show that this mixture closely resembles a mixture of two seeds, 
and supports the view that the storage tissues of plants aU resemble 
each other in their dietary properties. 

Lot 1397 shows the failure of the animals to grow when fed a 
mixture of corn and potato supplemented with the only inorganic 
salts necessary to complete its mineral content. That no other 
elements are necessary is made dear by the records of the other 
animals in this chart. 

Lot 1442; Period 1, shows that the addition of fat-soluble A, with- 
out salts, does not make growth possible on a mixture of potato and 
com kernel. In Period 2, growth took place at once on the addition 
of sodium chloride and calcium carbonate. 

Lot 1415, Periods I and 2, illustrate the fact that the addition of 



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LEGENDS TO THE CHARTS 185 

protein (casein) alone, or of protein, and fat-soluble A, respectively, 
does not make the mixture of potato and com kernel dietetically 
complete. In Period 3, when the necessary salts were added, growth 
took place at once. The rat whose curve is shown has successfully 
reared two litters of young (14) and her daughter, from the first 
litter, has weaned a Utter of seven yoimg. The daughter has been fed 
exclusively upon the diet of Period 3, since she was weaned. These 
results make it clear that this mixture of corn, casein, potato, butter 
fat and the two salts, forms a very satisfactory diet. 

Lot 1406 shows the ability of young rats to grow and reproduce at 
the normal rate and rear part of their young when confined to a diet 
of com and potato supplemented with fat-soluble A and two salts, 
calcium carbonate and sodium chloride. This record indicates t^t 
the proteins derived from these two sources are of fairly good biolog- 
ical value. The diet contains but 9 per cent of total crude protein 
(N x 6.25). If the protein were aU derived from the com kernel, this 
amount would not support such a good rate of growth, and no rearing 
of young. 

From the data available in our records, it is apparent that the 
potato is a very valuable food, a conclusion which is in harmony 
with the favor in which it has come to be regarded as an article of 
diet for man. 

Chart 15. — ^This and the following chart describe the relation of 
the mother as a factor of safety in the nutrition of her yoimg. In 
nearly all of these records the mother was fed during lactation, a diet 
which was faulty in some respect, and on which the young, after 
the weaning age, could not grow at all. The problem was to find 
to what extent the mother is able to take such faulty diets, and pro- 
duce milk of a character which will support growth in her young. 
The results show that the mother is capable under such dietary 
limitations of providing for her offspring a better diet for growth 
than she herself receives. 

The mothers were fed an excellent diet untU they delivered their 
young. The litter was in all cases reduced to four, in order to make 
the results comparable, and in order not to place an excessive burden 
upon the mother. From the day the young were bom the mother 
received the faulty experimental diet. 

Rat 211 illustrates the rate of growth of a litter of four young 
when the diet of the mother is highly satisfactory. This diet con- 



186 THE NEWER KNOWLEDGE OF NUTRITION 

tained a liberal amount of milk and of wheat, together with a salt 
mixture and butter fat. 

Rat 738 was fed nothing but rolled oats. Young after being 
weaned cannot grow at all on this diet. During the first 20 days the 
young grew slowly, then became stunted, and died between the 40th 
and 50th days. There are three types of deficiency in roUed oats: 
the inorganic content is unsatisfactory, the content of fatrsoluble A 
is very low, and the proteins are not of very high value for growth. 
Notwithstanding these deficiencies, the lactating mother was able 
to produce milk having considerable growth-promoting properties. 

Rat 843 was fed rolled oats with one of its deficiencies corrected, 
viz : by the addition of fat-soluble A. The growth curve of her young 
shows that her milk was of distinctly better quality than that which 
she could have produced from oats alone. The young grew faster 
and growth continued over a longer interval. Since the young eon- 
tinued to grow to the 50th day, it is evident that the mother was stiU 
supplementing the diet of oats and butter fat, which they began to 
eat at about the 20th day of age, with a considerable amount of 
milk which corrected the inorganic content of the oat kernel, for 
without the addition of calcium, sodium and chokine, rolled oats 
cannot support growth, even when its other deficiencies are corrected. 

Rat 983 did no better with her young on a diet of oats to which 
both protein and fat-soluble A were added, than did rat 843, with- 
out the protein addition. The first Umiting factor for the mother 
in milk production is the inorganic content, just as it is for growth 
in the young. 

Rat 899 did remarkably well in inducing growth in her young 
when her diet consisted of roUed oats and a suitable addition of salts 
for the correction of the inorganic deficiencies of the oat kernel. 
The seed is not entirely free from fat-soluble A, and the mother seems 
to have a reserve supply of this substance in her tissues which she 
can, for a time, contribute to her milk. 

Rat 1978, which was fed oats supplemented with salts and fat- 
soluble A, induced growth at a fairly good rate in her young. The 
60 per cent of oats in her diet furnished but 9 per cent of protein, 
and this did not suffice, because of its relatively low value, for the 
production of a normal milk supply. The growth of these young 
after the time they became able to eat of the mother's food supply, 
was much more rapid than it would have been had they not been 



LEGENDS TO THE CHARTS 187 

getting a supplementary milk supply from the mother during the 
period covered by the growth curve. 

Chart 16 contains further records of the growth of young which 
were suclding mothers on diets derived from rolled oats, supple- 
mented in various ways. 

Chart 16. — Continuing the records described in Chart 15. 

Rat 948 shows the failure of the young to develop beyond a lim- 
ited degree on a diet of rolled oats supplemented with protein only. 
The behavior of these young is comparable to that of Lot 738, 
Chart 16. The two most serious deficiencies of the oat kernel for 
milk production as for growth in the young, are the inorganic factor 
and the shortage of fat-soluble A. 

It was shown in Chart 8 that oat proteins combined with gelatin, 
form a highly satisfactory protein mixture. This is confirmed by 
the growth at half nonnal rate of the young of rat 949, whose diet 
consisted of roUed oats and gelatin. Yoimg rats cannot grow at 
all on this mixture. The mother is able to take such a faulty diet, 
and furnish milk of such a character as will safeguard her young in 
a most remarkable degree. Her limitations are, however, easily 
apparent. 

Rat 984 did slightly better in extending the lives of her young 
when she was fed rolled oats plus gelatin plus butter fat (fat-soluble 
A), than did rat 949, on the same food, minus the butter fat. It 
should be remembered that young rats cannot grow at all, if when, 
after being weaned, they are confined to this diet. The rdle of the 
tnother as a factor of safety in the nutrition of her young is easily 
seen. 

Rat 1020, which was fed oats, gelatin and salts, was limited only 
with respect to the relative shortage of fat-soluble A in her diet. 
Nevertheless, she was able to produce milk which could induce 
growth at a fairly good rate in her young. 

Rat 1019, was fed a diet which differed from that of 1020 only in 
containing casein. This appears to have had a slightly beneficial 
effect. 

Rat 980 was fed rolled oats plus 20 per cent of skim mUk powder. 
This amount was not sufficient to correct the inorganic deficiencies 
of the diet, and failed to supply enough fat-soluble A to render the 
diet satisfactory for milk production. It seems probable that the 
sodium chloride content and fat-soluble A in the skim milk powder 



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LEGENDS TO THE CHARTS 189 

were the limiting factors in preventing the production of normal milk 
in this case. , 

In answer to the question as to whether the failure of the young 
to grow on the milk they received in these experiments, was not the 
result of insuflSciency in quantity rather than quality of nulk, we 
have the observations on cows, which were fed insufBcient food 
during lactation, and in other experiments, in which cows were 
starved for common salt for periods of eight to fifteen months, and 
actually died or came near death from salt starvation. Unfler such 
conditions the milk flow was kept up over a long period in a most 
surprising manner. 

We have further evidence that the young rats in the experiments 
described, continued in some instances to grow long after they be- 
came able to eat of their mother's food, when the latter was of such 
a character as to permit of no growth whatever, had it not been 
supplemented with a considerable amount of milk from the mother. 
When it is considered that in some of these cases the yoimg weighed 
more than half as much as the mother, it must be admitted that the 
milk production, even in these greatly prolonged periods of lactation, 
while the mothers were taking faulty diets, must have been very 
considerable. 

The relation bet'yeen the character of the diet of the nursing 
mother and the character of the milk she produces has been dis- 
cussed in Chapter 6. 



BIBLIOGRAPHY 

Chapter I 

1. Fischer: Chemistry of the Proteins, Mann. 

2. Osborne, T. B. : The Vegetable Proteins. Monographs on 

Biochemistry, Longmans, Green and Company. 
3.' Atwater, W. A.: Bulletin 28, United States Department 
of Agriculture. 

4. Eijkman, C: Arch. f. Hyg., 1906, Iviii, 150. 

Arch. path. Anat., 1897, cxlviii, 523. 

5. Henriques and Hansen: Zeitschr. fiir physiol. chem., 1905, 

xliii, 417. 

6. Willcock, E.G., and Hopkinfi, F. G.: Jour. Physiol., 1906, 

XXXV, 88. 

7. Wise. Agric. Expt. Sta., Research Bull., No. 17 (1911). 

8. McCollum, E. V., and Davis, M.: Jour. Biol. Chem., 1913, 

XV, 167. 

9. Stepp, W.: Biochem. Ztschr., 1909, xxii, 452; Ztschr. f. 

Biol., 1912, Ivii, 135; Ibid, 1912-1913, lix, 366. 

10. Hopkins, F. G.: Jour. Physiol., 1912, xliv, 425. 

11. Funk, C: Lancet, London, 1911, ii, 1266. 

12. Eraser, H., and Stanton, A. T.: Lancet, London, March 12, 

1910, 733; The Etiology of Beri-Beri, Study 12, from 
the Institute for Medical Research, Federated Malay 
States, 1911. 

13. McCollum and Davis: Join-. Biol. Chem., 1915, xxiii, 247; 
McCollum, E. v., Simmonds, N . , and Pitz, W. : Ibid, 1916, 

XXV, 105. 

14. Funk and Macallum: Jour. Biol. Chem., 1915, xxiii, 419. 

15. Henry, W. A.: Wisconsin Agric. Expt. Sta., Annual Re- 

port, 1889, 15. 

191 



192 BIBLIOGRAPHY 

16. Funk, C: J. State Med., 1912, xx, 341; Biochem. Bull., 

1915, iv, 304. 

17. McCoUum and Davis: Jour. Biol. Chem., 1915, xxiii, 181. 

18. McCoUum and Davis: Jour. Biol. Chem., 1915, xxiii, 231. 

19. McCoUum, E. V., and Kennedy, C: Jour. Biol. Chem., 

1916, xxiv, 491. 

20. Osborne, T. B., and Mendel, L. B.: Jour. Biol. Chem., 

1913, xvi, 431. 

Chaptek II 

1. McCoUum, Simmonds and Pitz: Jour. Biol. Chem., 1917, 

xxix, 341. 

2. Smith, Theobold: Bureau of Animal Industry, "BacUli in 

Swine Disease, 1895-1896, 172. 

3. Hoist, A., and Frolich, T.: Z. Hyg. u. Infektionskrankh, 

1913, ixxv, 334. 

4. McCoUum and Pitz: Jour. Biol. Chem., 1917, xxxi, 229. 

5. McCoUum and Simmonds: Jour. Biol. Chem., 1917, xxxii, 

181. 

6. McCoUum and Simmonds: Jour. Biol. Chem., 1918, 

xxxiii, 55. 

7. Hart, E. B., McCoUum, E. V., Steenbock, H., and Hum- 

phery, G. C: Wise. Agric. Expt. Sta. Research BuU., 
' 17, 1911. 

Hart and McCoUum: Jour. Biol. Chem., 1914, xix, 373. 
McCoUum and Davis: Jour. Biol. Chem., 1915, xxi, 615. 
McCoUum, Simmonds and Pitz: Ibid, 1916-1917, xxviii, 

211. 

8. Hart and McCoUum: Jour. Biol. Chem., 1914, xix, 373. 
McCoUum, Simmonds and Pitz: Ibid, 1916, xxviii, 153. 

9. McCoUum, E. V., Simmonds, N., and Parsons, H. T.: 

Unpublished data. 
10. McCoUum, E. V. : Jour. Am. Med. Assn., 1917, bcviii, 1379. 
Harvey Lecture Series 1916-1917 — ^also — ^Unpublished 
data. 



BIBLIOGRAPHY 193 

11. McCollum, Simmonds and Pitz: Jour. Biol. Chem., 1917, 

xxix, 521. 

12. McCoUiim, Siminonds and Pitz: Jour. Biol. Chem., 1917, 

XXX, 13. 

Chapteb III 

1. Slonaker, J. R.: Leland Stanford Junior University, Pub. 

Univ. Series, 1912. 

2. MeCollum, Simmonds and Pitz: Jour. Biol. Chem., 1917, 

X3CX, 13. 

3. McCollum, Simmonds and Pitz: Am. Jour. Physiol., 1916, 

xliv, 333. 

4. Eward, J. M.: Proc. Iowa Acad. Sci., 1915, xxii, 375. 

5. Loeb, J.: The Dynamics of Living Matter, New York, 

1906. 

6. Howell, W. H.: Am. Jour. Physiol., 1899, ii, 47; 1902, vi, 

181. 

Chapter IV 

1. McCollum, E. v.: Jour. Biol. Chem., 1914, xix, 323. 

2. McCollum and Simmonds: Jour. Biol. Chem., 1917, xxxii, 

347. 

3. McCollum and Davis: Jour. Biol. Chem., 1915, xx, 415. 

4. McCoUiun, Simmonds and Parsons: Unpublished data. 

Chapter V 

1. McCoUum and Kennedy: Jour. Biol. Chem., 1916, xxiv, 

491. 

2. Osborne and Mendel: Jour. Biol. Chem., 1913, xvi, 431. 

3. McCollum and Siomionds: Jour. Biol. Chem., 1917, xxxii, 

347. 

4. McCollum, Simmonds and Parsons: Unpublished data. 

5. Herdlika, A.: Bulletin 34, Bureau of American Ethnology. 



194 BIBLIOGRAPHY 

6. Mori, M.: Jahrb. Kinderheilk, 1904, lix, 175. 

7. Bloch, C. E.: Ugeskruft fur Laeger, 1917, kxix, 349, cited 

from Jour. Am. Med. Assn., 1917, kviii, 1516. 

8. Czerny, A. and Keller, A. : Des Kindes, Leipsic,, 1906, pt. 

2,67. 

9. Little, A. D.: Jour. Am. Med. Assn., 1912, Iviii, 20129. 

10. Walcott, A. M.: Jour. Am. Med. Assn., 1915, brv, 2145. 

11. Eijkman, C: Arch. f. Hyg., 1906, Iviii, 150. 

Arch. Path. Anat., 1897, cxlviii, 523. 

12. Funk, C: Lancet, London, 1911, ii, 1266. 

13. Funk and Macallum: Jour. Biol. Chem., 1915, xxiii, 419. 

14. Williams, R. R.: Jour. Biol. Chem., 1916, xxv, 437; 1916, 

xxvi, 431; 1917, xxix, 495. 

15. Jackson, L., and Moore, J. J. : Jour. Infect. Dis., 1916, xix, 

478. 

16. McColIum and Pitz: Jour. Biol. Chem., 1917, xxxi, 229. 

17. Hess, A. F.: Am. Jour. Dis. of Children, 1917, xiv, 337. 

18. Goldberger, Joseph: Jour. Am. Med. Assn., 1916, Ixvi, 471. 

19. Jobling, J. W., and Peterson, "W. : Jour. Infect. Dis., 1916, 

xviii, 501. 

20. Thompson-MacFadden Commission, Siler, J. F., Garri- 

son, P.E.,and McNeal, W. J.: Arehiv. Int. Med. Oct. 

1914, p. 453; Joum. Amer. Med. Assn. Sept. 26, 1914, 
p. 1090. 

21. Goldberger, Joseph: Public Health Reports, November 17, 

1916, pp. 3159-3173. 

22. Goldberger, Joseph: Public Health Reports, Nov. 12, 

1915, p. 3. 

23. Chittenden, R. H., and Underbill, F. P. : Am. Jour. Physiol., 

1917, xliv, 13. 

24. McCoUum, Simmonds and Parsons: Jour. Biol. Chem., 

1918, xxxiii, 411. 

25. McCollum and Simmonds: Jour. Bioil. Chem., 1917, 

xxxii, 29. 

26. Hess, A. F.: Jour. Am. Med. Assn., 1918, Ixx, 900. 



BIBLIOGRAPHY 195 

Chaptbe VI 

1. McCollum and Simmonds: Am. Jour. Phys., 1918, xlvi, 

275. 
McCollum, Simmonds and Pitz : Jour. Biol. Chem., 1916, 
xxvii, 33. 

2. Osborne and Mendel: Jour. Biol. Chem., 1915, xx, 379. 

3. Andrews, V. L. : Philippine Jour. Science, Series B, 1912, 

vii, 67. 

4. Babcock, S. M. : Twenty-Second Annual Report of Wis- 

consin Experiment Station, 1905, 129. 

5. Eckles, C. H., and Palmer, L. S. : Missoiui Agric. Expt. 

Station Research Bull., 25, 1916. 

6. Ducaisne, E.: Gaz. Med., Paris, 1871, 317. 

Chapter VII 

1. Osborne and Mendel: jour. Biol. Chem., 1915, xx, 381. 

2. McCollum and Davis: Jour. Biol. Chem., 1915, xxiii, 247. 

3. McCollum, Simmonds and Pitz: Jour. Biol. Chem., 1917, 

xxix, 521. 

4. Sullivan, M. X., and Voegtlin, C. : Jour. Biol. Chem., 1916, 

xxiv, xvi. 

5. Simpson and Edie: 1911-12, Ann. Trop. Med. and Parasit., 

V, 321. 
Ohler: Jour. Med. Research, 1914, xxxi, 239. 

6. Withers and Carrath: Jour. Agric. Research, 1915, v, 261. 

Jour. Biol. Chem., 1917, xxxii, 245. 

7. McCollum and Davis: Jour. Biol. Chem., 1915, xxiii, 231. 

8. McCollum and Simmonds: 1917, xxxii, 181. 



INDEX 



Alfalfa flour, 41, 167, 169, 179 Dietary essentials, chemically 

Alkaloids, 4 unidentified, 23, 34, 47 

Amino-aoids, 5, 74, 75 Dietary habits, 139 

Appetite, importance of in the Diets from single plant sources. 



10 
Diets, simplified, 9, 14, 15, 16, 

19, 155 
Disease and diet, 6, 30, 36, 87, 

95, 103, 139 
i)iseases, deficiency, 83-87, 91, 

95, 114 



selection of food, 64 

Barley, 38 

Bean, navy, 38, 181 

Bean, soy, 38, 175 

Beri-beri, 7, 20, 28, 83, 90 

Biological method for the anal- 
ysis of food-stuffs, 20, 21, 56, 
113, 161 

Butter fat, 16, 89 

Camivora, dietary habits of, 78 
Cereal grains, 157, 161 
Chittenden and Underhill, stud- 
ies of pellagra, 107 
Corn, 10, 173 '' 
Cotton seed flour, 142, 143 

Deficiency diseases, 83-87, 91 
95, 114 

Diet and disease, 6, 7 

Diet, essential factors in, 31 

Diet of nursing mother in rela- 
tion to the quality of her Foods, physical properties of, 
milk, 116-129, 185-189 15 

Diet, planning of adequate, 130 Foods, proteetive7 82, 141, 147, 

Diet, monotonous, 7 149 

Dietary essentials, nomenela- Foods-stuffs, biological analysis 
ture of unidentified, 32 of, 20, 21, 56 

197 



s, 80 
Eijkman, 7 
Eward, studies on appetite, 64 

Fats, 2, 3, 4 

Fats, butter, 16 

Fats, egg yolk, 16 

Fats, lard, 16 

Fats, vegetable, 16 

Fat-soluble A, 23, 34, 47, 89, 

145, 155 
Flax seed, 38 
Food analysis, 5 
Foods, effect of cooking on, 

135-138 



198 



INDEX 



Food-stuffs, supplementary re- 
lationships among, 61, 71, 81 
Eraser and Stanton, 19 
Fruits, 7, 142 
Funk, 19 

Gelatin, 171 

Glandular organs, 79 

Gliadin, 8 

Goldberger, studies of pellagra, 

105-107 
Growth, impetus to, 72 

Henriques and Hansen, stud- 
ies of simplified diets, 8 
Hess, studies of scurvy, 100 
Hoist, studies of scurvy, 34 
Hopkins, studies of simplified 

diets, 18 
Hormones, 85 

Inorganic salts, importance of, 

4,22 
Iron, 69 

Jobling and Peterson, studies 
of pellagra, 105-106 

Kafir corn, 38 

Leaf, dietary properties of, the, 

41, 44, 53, 77 
Leaf and seed mixtures, dietary 

properties of, 61, 167 
Lipoids, 3, 17 

Meats, 6, 8, 76 
Milk, 6, 8, 76 

Milk, place of in the diet, 150- 
153 



Milk, production, 12 

Milk, quaUty of, as influenced 

by diet, 116-129, 185-189 
Millet seed, 38, 175, 177 
Muscle tissue, 6, 8, 76 
Nomenclature of the chemically 

unidentified dietary essentials, 

84 

Osborne and Mendel, 87 

Pasteurization of milk, 100-103 
Peanut, 142 
Peas, 38, 177, 181 
Pellagra, 7, 30, 103 
Pellagra-producing diets, 108 
Polyneuritis, 19, 20, 28 
Potato, proteins of, 135, 181 
Proteins, 2, 3, 4, 5 
Proteins, biological values of, 

5, 24, 74, 75 
Proteins, quality not shown by 

chemical analysis, 113 

Rat, domestic, 14 

Rat, domestic, growth of, 14 

Rat, reproduction in, 14 

Rice, dietary properties of, 27, 

38, 159, 161 
Rickets, 111 
Roots, edible, 47 
Rye, dietary properties of, 38, 

175 

Salts, 4 

Scurvy, 7, 30, 34, 36, 37, 95-103 
Seed, biological properties of, 53 
Seed, and leaf mixtures, dietary 
properties of, 61 



INDEX 199 

Seeds, dietary properties of, 6, Variety not a safeguard in. nutri- 

165 tion, 66 

Slonaker, studies of vegetarian Vegetable oils, 16 

diet, 57 Vegetables, 6, 7 

Smith, Theobald, scurvy in the Vegetarian diet, 50, 53 

guinea pig, 34 

Sodium, lack of su£Scient, in Water, 4 

seeds, 23, 49 Water-soluble B, 29, 34, 47, 

Starch, 2, 3, 4 155 

Stepp, studies of dietary prop- Wheat and other cereals com- 

erties of lipoids, 17 pared, 139 

Wheat, dietary properties of, 

Thompson-McFadden-Commis- 10, 20, 21, 38, 157, 159, 171, 

sion, studies of pellagra, 106 175, 179 

Tubers, dietary properties of. Wheat flour, bolted, 140 

6, 45 Wheat flour, whole, 140 

Unidentified factors in the diet. Xerophthalmia of dietary origin, 

17, 18 87, 139 



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